This website called stu nicholls | CSS PLaY | experiments with cascading style sheets is getting a lot of attention lately. Rich Sias sent it to me, and Frank Stepanski has noted it.
The site is all about CSS and stretching its limits. Some of the examples are interactive items that one might usually associate with scripting. And it appears so far that the cross browser support is excellent.
I hope to be using some of these examples in upcoming CSS workshops.