Dan Cederholm, of SimpleBits fame, recently releases Pears,
an open source WordPress theme for creating your own markup & style pattern library
What a fantastic idea. This is a very niche theme, not trying to be everything to everyone, but clearly made with solving a particular problem in mind. It’s also well designed, as can be expected from Mr. Cederholm’s works. The project is also available in Github. (Oh, and it’s open sourced, of course).