The Y-Combinator startup believes that you should be able to post everything to your blog using email--whether you're uploading pictures, video, audio or just text. A noble gesture it was, but with one fatal flaw: Posterous blogs had no themes. That's right: they were blank white.
This isn't all bad, because Posterous lets you "re-blog" to a bevvy of other services, so you can post to your Tumblr account, Twitter, Drupal, Wordpress, Blogger, and more. Your actual Posterous remained a lame blank archive until today, when the company announced on its blog  that it was adding pre-set and customizable themes.
Like Tumblr, Posterous will let you easily alter colors, but also gives you the ability to upload your own header. If you're more code-friendly, you can get in a code up a fancy-pants theme all yourself. There are only five themes--Tumblr has dozens--but presumably there are more to come.