I've been playing a lot with Wordpress recently. I touched up the Arthemia theme on the Agile Edmonton site, moved my site from the Copyblogger theme to the Vigilance theme, customized the Vigilance theme a bit and then wrote up a couple of widget plugins for my sidebar.
One thing that I really like about the Wordpress framework is that I can play around with it quite a bit despite the fact that I'm just learning PHP. The ease of customization was actually an unexpected bonus - I chose Wordpress because of the number of themes that are available for it. While I like playing with design, I'm not very good at it so it was a bonus for me that Wordpress has such a huge number of available themes.