If you're into web design, then you definitely heard about 'CSS Zen Garden'.According to the Zen Garden it's:

A demonstration of what can be accomplished visually through CSS-based design.

In short it's a place where web designers can show off their skills and designs. You take the plain HTML markup they give you, work on a design, style the HTML you took with CSS without changing a single bit in the HTML. It's pretty challenging and that's why you see wonderful submissions from around the world...

My favorite was the "Retro Theatre" theme. Until I saw the "Geocities 1996" one. Watch out before viewing it...It can hurt your eyes :P The author said he was nostalgic when he decided to create this beautifull mess, I mean design :D. He's brilliant!

I hope this motivates you to submit your own Zen Garden CSS Design.