OK, I'm a little late coming to the party sometimes, so I'm only just now getting around to checking out things like Failblog, but I'm a big fan.
If you're a little slow like me and you're looking for a chuckle, you might also check out these:
thereifixedit.com cakewrecks.com ugliesttattoos.com thisisphotobomb.com/ The last two aren't necessarily always safe for work or around kids; in fact, Photobomb leans toward the raunchy a lot of the time. (Not that there's anything wrong with that....)
Let me know if you have any suggestions of your own. Reality is so much funnier than comedy.