Coverpop!
Imagine a very large coffee table strewn with magazines or books, but you can point at any one of them and it flies up and into full view right away.
Now imagine the coffee table as a web page, and you've got Coverpop, yet another great webhack from Jim Bumgardner.
I also really enjoyed Jim's CoverPop - How it Works post, with (partially) gory details about Perl, ImageMagick, Flash/ActionScript, etc.