Caveman's Crib: http://www.cavemanscrib.com/
Spend some time snooping around in their apartment. Change the channels on their TV, look through their bathroom drawers. Listen in on their phone conversations.
It's totally interactive and there are a lot of hidden treasures around, so take your time.
Elf Yourself: http://www.elfyourself.com/
This site is really old news, but some of you may not have heard of it.
Make an elf of yourself and others. It's what Christmas is all about.
Demotivation: http://www.despair.com/
It's not as bad as it sounds, but the humor is a little dark.
Check it out if you're feeling overly motivated and need a little bring-me-down.
this is becoming all the rage:
http://www.readymech.com/
just click on the little toy and you can download the pdf and print your own! it's a great time-killer.
Awesome site! Thanks for the tip.