I have been playing with some cool CSS3 and HTML5 technologies. Here are some of the links I have playing with!
http://www.standardista.com/hack-for-css3-supporting-browsers - Here's a hack for supporting CSS3 without compromising older browsers.
http://html5test.com/ - Some sort of weird test to see how well your browser support HTML5 and CSS3 rules. I scored 101/160 in Firefox 3.6. Source code is available!
http://net.tutsplus.com/tutorials/html-css-techniques/5-techniques-to-acquaint-you-with-css-3/ - A cool CSS3 tutorial.
http://www.zachstronaut.com/projects/rotate3di/ - Super cool 3d rotate plugin (much better than jQuery Flip if you have the CSS3 support)