Just posted a couple of my themes at themes.posterous.com. Was planning on getting them up like a month ago, but then life got in the way and they didn't happen, but now they're finally done. If you're a Posterous user and haven't gotten into the theming game/want to make your Posterous prettier, you should try it out! Just go here and follow the directions.
Here are screenshots of the new themes, designed and coded by yours truly: