This is definitely one of the coolest sites I've ever seen.
It's guimp.com - the World's Smallest Website.
It's way cool, but you're going to strain your eyes. All the content on the site is contained in a square 18 pixels by 18 pixels. They do have lots of content though - breakout, pong, pacman, asteroids, tic-tac-toe, pinball, and I don't know how many more.
Check it out, but grab a magnifying glass.