I just switched the default theme of this blog to the latest K2 theme by Michael Heilemann at binarybonsai.com. Michael created the Kubrick theme that I was using before (and which was also adopted as the default for all new WordPress installations).
K2 is a really nice design, with some great thought to functional layout. It supports a boatload of useful plugins, and displays their magic if they are installed.
Check out the cool ajax-powered search dealie - just start typing a query, and out pops a list of matches. Pretty cool. Comment submission also uses some ajax juju, but it's a bit funky at the moment, and isn't quite fully baked yet. Still, quite cool.