I can't wait to be able to use advanced CSS on my pages, but it is now IE5/6 that are the NS4's of the time.
css play has some great CSS code to work with like the CSS Layout with Columns, but it is completely wrong in IE.

I love the idea of being able to enlarge images using CSS and I guess it would aid in navigation, but again its IE that will make it look completely stupid with a grey outline.

Another cool thing in the drafted CSS3 is "Mark your jump", which allows the text to be highlighted or boxed with the :target pseudo-class.

I just spotted something that I didn't know existed, pop-up menus in CSS using NO javascript. It half works in IE too with the bottom links clickable, but no popup/dropdowns visible.

CSS click menu is just plain weird, but it would be cool as a hidden Easter egg on a site or something.

If you would like to learn a lot more about CSS, then I suggest you check out DeSilva's CSS Tutorials

Rob!