Even before the www was invented, people were swapping jokes across the internet, and the best ones ended up on the Usenet newsgroup rec.humor.funny. Their archives are at http://www.netfunny.com/rhf/ .
Old Jews Telling Jokes Edit
http://oldjewstellingjokes.com/ is just what it says: videos of old jews telling jokes, "a new (old) joke every Tuesday and Thursday".
Quote Database (QDB) Edit
http://www.bash.org/ has funny quotes from all kinds of chats, from irc chat channels to icq conversations. Lots of people send quotes in, only few get published.