I've been using Thesis on Weekly Web Tools and the School of Podcastingfor about a year. It's a great WordPress Theme that is really customizable. The one thing that I always wanted was the ability to change the color of the tabs at the top of the page. Well with it's latest release, Thesis makes it very easy to make changes to the menu system, but also taps into the parent/child feature of both pages and categories to really allow you to completely control what shows/hides in the menu.
Throw this into the ability to change the shape, size, and number of columns and you may see Thesis return to this very blog (the theme I have right now I designed with Artisteer).
Watch this video so see how easy it is to chagne the colors.