diff --git a/r2/r2/controllers/api.py b/r2/r2/controllers/api.py
index e7335ec0e..edad3bd9b 100644
--- a/r2/r2/controllers/api.py
+++ b/r2/r2/controllers/api.py
@@ -29,7 +29,7 @@ from validator import *
 from r2.models import *
 import r2.models.thing_changes as tc
 
-from r2.lib.utils import get_title, sanitize_url, timeuntil
+from r2.lib.utils import get_title, sanitize_url, timeuntil, set_last_modified
 from r2.lib.wrapped import Wrapped
 from r2.lib.pages import FriendList, ContributorList, ModList, \
     BannedList, BoringPage, FormPage, NewLink
@@ -278,6 +278,10 @@ class ApiController(RedditController):
         if should_ratelimit:
             VRatelimit.ratelimit(rate_user=True, rate_ip = True)
 
+        #update the modified flags
+        set_last_modified(c.user, 'overview')
+        set_last_modified(c.user, 'submitted')
+        
         # flag search indexer that something has changed
         tc.changed(l)
 
@@ -598,6 +602,12 @@ class ApiController(RedditController):
             # flag search indexer that something has changed
             tc.changed(item)
 
+            #update last modified
+            set_last_modified(c.user, 'overview')
+            set_last_modified(c.user, 'commented')
+            set_last_modified(link, 'comments')
+
+
         #set the ratelimiter
         if should_ratelimit:
             VRatelimit.ratelimit(rate_user=True, rate_ip = True, prefix = "rate_comment_")
@@ -623,6 +633,10 @@ class ApiController(RedditController):
             organic = vote_type == 'organic'
             Vote.vote(user, thing, dir, ip, spam, organic)
 
+            #update last modified
+            set_last_modified(c.user, 'liked')
+            set_last_modified(c.user, 'disliked')
+
             # flag search indexer that something has changed
             tc.changed(thing)
 
diff --git a/r2/r2/controllers/error.py b/r2/r2/controllers/error.py
index 5cc74cb33..3e49a2c83 100644
--- a/r2/r2/controllers/error.py
+++ b/r2/r2/controllers/error.py
@@ -128,21 +128,18 @@ class ErrorController(RedditController):
                                    content=pages.UnfoundPage(choice=ch))
             return res.render()
 
-    def send503(self):
-        c.response.status_code = 503
-        c.response.headers['Retry-After'] = 1
-        c.response.content = toofast
-        return c.response
-
     def GET_document(self):
         try:
             code =  request.GET.get('code', '')
-            if code == '500':
+            if code == '403':
+                return self.send403()
+            elif code == '500':
                 return redditbroke % rand_strings.sadmessages
             elif code == '503':
-                return self.send503()
-            elif code == '403':
-                return self.send403()
+                c.response.status_code = 503
+                c.response.headers['Retry-After'] = 1
+                c.response.content = toofast
+                return c.response
             elif c.site:
                 return self.send404()
             else:
diff --git a/r2/r2/controllers/front.py b/r2/r2/controllers/front.py
index 616579328..3f9835cbf 100644
--- a/r2/r2/controllers/front.py
+++ b/r2/r2/controllers/front.py
@@ -97,6 +97,9 @@ class FrontController(RedditController):
         if not c.default_sr and c.site._id != article.sr_id: 
             return self.abort404()
 
+        #check for 304
+        self.check_modified(article, 'comments')
+
         # if there is a focal comment, communicate down to comment_skeleton.html who
         # that will be
         if comment:
@@ -185,6 +188,7 @@ class FrontController(RedditController):
 
         # overview page is a merge of comments and links
         if location == 'overview':
+            self.check_modified(vuser, 'overview')
             links = Link._query(Link.c.author_id == vuser._id,
                                 Link.c._spam == (True, False))
             comments = Comment._query(Comment.c.author_id == vuser._id,
@@ -192,11 +196,13 @@ class FrontController(RedditController):
             query = thing.Merge((links, comments), sort = db_sort, data = True)
 
         elif location == 'comments':
+            self.check_modified(vuser, 'commented')
             query = Comment._query(Comment.c.author_id == vuser._id,
                                    Comment.c._spam == (True, False),
                                    sort = db_sort)
 
         elif location == 'submitted':
+            self.check_modified(vuser, 'submitted')
             query = Link._query(Link.c.author_id == vuser._id,
                                 Link.c._spam == (True, False),
                                 sort = db_sort)
@@ -204,6 +210,7 @@ class FrontController(RedditController):
         # (dis)liked page: pull votes and extract thing2
         elif ((location == 'liked' or location == 'disliked') and
               votes_visible(vuser)):
+            self.check_modified(vuser, location)
             rel = Vote.rel(vuser, Link)
             query = rel._query(rel.c._thing1_id == vuser._id,
                                rel.c._t2_deleted == False)
diff --git a/r2/r2/controllers/reddit_base.py b/r2/r2/controllers/reddit_base.py
index a4dd53d6c..20d7b4e24 100644
--- a/r2/r2/controllers/reddit_base.py
+++ b/r2/r2/controllers/reddit_base.py
@@ -392,7 +392,6 @@ class RedditController(BaseController):
                 c.used_cache = True
                 # response wrappers have already been applied before cache write
                 c.response_wrappers = []
-                
 
     def post(self):
         response = c.response
@@ -421,6 +420,16 @@ class RedditController(BaseController):
             config.cache.set(self.request_key(),
                              response,
                              g.page_cache_time)
+    
+    def check_modified(self, thing, action):
+        if c.user_is_loggedin:
+            return
+
+        date = utils.is_modified_since(thing, action, request.if_modified_since)
+        if date is True:
+            abort(304, 'not modified')
+        else:
+            c.response.headers['Last-Modified'] = utils.http_date_str(date)
 
     def abort404(self):
         abort(404, 'not found')
diff --git a/r2/r2/lib/base.py b/r2/r2/lib/base.py
index f4fa39dd6..a243bdd70 100644
--- a/r2/r2/lib/base.py
+++ b/r2/r2/lib/base.py
@@ -26,7 +26,7 @@ from pylons.i18n import N_, _, ungettext, get_lang
 import r2.lib.helpers as h
 from r2.lib.utils import to_js
 from r2.lib.filters import spaceCompress
-from utils import storify, string2js
+from utils import storify, string2js, read_http_date
 
 import re, md5
 from urllib import quote 
@@ -65,6 +65,12 @@ class BaseController(WSGIController):
         request.path = environ.get('PATH_INFO')
         request.user_agent = environ.get('HTTP_USER_AGENT')
         request.fullpath = environ.get('FULLPATH', request.path)
+        
+        if_modified_since = environ.get('HTTP_IF_MODIFIED_SINCE')
+        if if_modified_since:
+            request.if_modified_since = read_http_date(if_modified_since)
+        else:
+            request.if_modified_since = None
 
         #set the function to be called
         action = request.environ['pylons.routes_dict'].get('action')
diff --git a/r2/r2/lib/utils/__init__.py b/r2/r2/lib/utils/__init__.py
index 15bb3a57e..ddf6594af 100644
--- a/r2/r2/lib/utils/__init__.py
+++ b/r2/r2/lib/utils/__init__.py
@@ -20,6 +20,8 @@
 # CondeNet, Inc. All Rights Reserved.
 ################################################################################
 from utils import *
+from http_utils import *
+from thing_utils import *
 
 try:
     from r2admin.lib.admin_utils import *
diff --git a/r2/r2/lib/utils/http_utils.py b/r2/r2/lib/utils/http_utils.py
new file mode 100644
index 000000000..5613fa488
--- /dev/null
+++ b/r2/r2/lib/utils/http_utils.py
@@ -0,0 +1,21 @@
+import pytz
+from datetime import datetime
+
+DATE_RFC822 = '%a, %d %b %Y %H:%M:%S %Z'
+DATE_RFC850 = '%A, %d-%b-%y %H:%M:%S %Z'
+DATE_ANSI = '%a %b %d %H:%M:%S %Y'
+
+def read_http_date(date_str):
+    try:
+        date = datetime.strptime(date_str, DATE_RFC822)
+    except ValueError:
+        try:
+            date = datetime.strptime(date_str, DATE_RFC850)
+        except ValueError:
+            date = datetime.strptime(date_str, DATE_ANSI)
+    date = date.replace(tzinfo = pytz.timezone('GMT'))
+    return date
+
+def http_date_str(date):
+    date = date.astimezone(pytz.timezone('GMT'))
+    return date.strftime(DATE_RFC822)
diff --git a/r2/r2/lib/utils/thing_utils.py b/r2/r2/lib/utils/thing_utils.py
new file mode 100644
index 000000000..081846242
--- /dev/null
+++ b/r2/r2/lib/utils/thing_utils.py
@@ -0,0 +1,32 @@
+from datetime import datetime
+import pytz
+
+def make_last_modified():
+    last_modified = datetime.now(pytz.timezone('GMT'))
+    last_modified = last_modified.replace(microsecond = 0)
+    return last_modified
+
+def is_modified_since(thing, action, date):
+    """Returns true if the date is older than the last_[action] date,
+    which means a 304 should be returned. Otherwise returns the date
+    that should be sent as the last-modified header."""
+    from pylons import g
+    
+    prop = 'last_' + action
+    if not hasattr(thing, prop):
+        last_modified = make_last_modified()
+        setattr(thing, prop, last_modified)
+        thing._commit()
+    else:
+        last_modified = getattr(thing, prop)
+
+    if not date or date < last_modified:
+        return last_modified
+    
+    #if a date was passed in and it's equal to last modified
+    return True
+
+def set_last_modified(thing, action):
+    from pylons import g
+    setattr(thing, 'last_' + action, make_last_modified())
+    thing._commit()
diff --git a/r2/r2/lib/utils/utils.py b/r2/r2/lib/utils/utils.py
index 2cc322a29..e5f31b86e 100644
--- a/r2/r2/lib/utils/utils.py
+++ b/r2/r2/lib/utils/utils.py
@@ -26,6 +26,7 @@ from copy import deepcopy
 import cPickle as pickle
 import re, datetime, math, random, string, sha
 
+from datetime import datetime, timedelta
 
 from pylons.i18n import ungettext, _
         
@@ -369,7 +370,7 @@ def timeago(interval):
              month  = 60 * 60 * 24 * 30,
              year   = 60 * 60 * 24 * 365)[period]
     delta = num * d
-    return datetime.datetime.now(g.tz) - datetime.timedelta(0, delta)
+    return datetime.now(g.tz) - timedelta(0, delta)
 
 def timetext(delta, resultion = 1, bare=True):
     """
@@ -386,7 +387,7 @@ def timetext(delta, resultion = 1, bare=True):
       (60, lambda n: ungettext('minute', 'minutes', n)),
       (1, lambda n: ungettext('second', 'seconds', n))
     )
-    delta = max(delta, datetime.timedelta(0))
+    delta = max(delta, timedelta(0))
     since = delta.days * 24 * 60 * 60 + delta.seconds
     for i, (seconds, name) in enumerate(chunks):
         count = math.floor(since / seconds)
@@ -394,7 +395,7 @@ def timetext(delta, resultion = 1, bare=True):
             break
 
     from r2.lib.strings import strings
-    if count == 0 and delta.seconds == 0 and delta != datetime.timedelta(0):
+    if count == 0 and delta.seconds == 0 and delta != timedelta(0):
         n = math.floor(delta.microseconds / 1000)
         s = strings.number_label % (n, ungettext("millisecond", 
                                                  "milliseconds", n))
@@ -412,11 +413,11 @@ def timetext(delta, resultion = 1, bare=True):
 
 def timesince(d, resultion = 1, bare = True):
     from pylons import g
-    return timetext(datetime.datetime.now(g.tz) - d)
+    return timetext(datetime.now(g.tz) - d)
 
 def timeuntil(d, resultion = 1, bare = True):
     from pylons import g
-    return timetext(d - datetime.datetime.now(g.tz))
+    return timetext(d - datetime.now(g.tz))
 
 
 def to_base(q, alphabet):
@@ -667,7 +668,7 @@ def find_broken_things(cls,attrs,time,delete = False):
         for Things of that class, missing those attributes, deleting
         them if requested
     """
-    for t in fetch_things(cls,time,datetime.datetime.now()):
+    for t in fetch_things(cls,time,datetime.now()):
         for a in attrs:
             try:
                 # try to retreive the attribute
@@ -694,7 +695,6 @@ def timeit(func):
 def lineno():
     "Returns the current line number in our program."
     import inspect
-    from datetime import datetime
     print "%s\t%s" % (datetime.now(),inspect.currentframe().f_back.f_lineno)
 
 class IteratorChunker(object):
diff --git a/r2/r2/models/account.py b/r2/r2/models/account.py
index 3a56512ae..86bb94e71 100644
--- a/r2/r2/models/account.py
+++ b/r2/r2/models/account.py
@@ -57,9 +57,9 @@ class Account(Thing):
                      report_ignored = 0,
                      spammer = 0,
                      sort_options = {},
-                     has_subscribed = False
+                     has_subscribed = False,
                      )
-    
+
     def karma(self, kind, sr = None):
         suffix = '_' + kind + '_karma'