CSS3 Animation
I absolutely love CSS3 animation, and I think it has great potential. While it is somewhat if a niche thing now, it can really make a site complete. An example of such is the Activate site, which was designed by Elliot Jay Stocks. Inspired by the CSS animation experiments of Anthony Calzadilla, I decided to create a little CSS3 animation of my own. Granted, it is a pretty simple animation, but nonetheless, it is a start.
(As an FYI, at this moment, this animation works wonderfully in a Webkit based browser, such as Chrome or Safari. In theory it should work in the latest and greatest version of Firefox, as well as in IE10, although I have not tested these.)