I’ve known about this site for a while but I thought I would mention it here for all of you who haven’t heard of it and who know at least a little HTML.
I’ve never seen Cascading Style Sheets do so much. Check out the CSS Zen Garden. Essentially, it exists to showcase the power of cross-browser compatible CSS. If you know and care what I’m talking about, this is a must-see site.
The site allows you to view its contents using any one of, I think, 135 style sheets.