Just in case you've got the mid-week blahs, here is a short list of some fun websites:
The Onion, which bills itself as America's Finest Newsource (it's funny, it's dry, it's the Onion!)
Hallmark - check out their free e-cards, many of which are very cool, and some are pretty funny.
Time's Cartoons of the Week (political cartoons)
Check out Lifehacker.com for ingenious, amusing and sometimes silly ideas to make your life better, more productive or less boring.
Be amazed at the London Book Project, which uses the London Underground system to distribute (and register) free books in a massive book exchange project. A little reminiscent of BookCrossing.com.
Get a cute fix at CuteOverload.com or TheCuteProject.com.
Play with music at CreatingMusic.com (this is a kids' site but it's fun, anyway!)