Hongkiat has a list of the current top 49 themes by download from Themes.WordPress.net. The list includes some of my favorites, as well as some that I think shouldn’t be on the list, but if you are looking to get a good theme, or avoid themes that everyone and their brother are using, this list might help you there.
I look forward to seeing what this list looks like in half a year, or even a year from now. Hopefully, one of the themes released from the Bloggy Network will be in with such a great group of themes.