I've decided to take on something quite difficult: I'm going to *attempt* to create an HTML5+CSS3 (graceful fallback) template which works beautifully on both Blogger and Posterous for my blog, SWDD. I've got a preliminary Webkit-centric layout mocked up already (complete with subtle, yet enjoyable webkit-transitions), and I just need to correlate the Webkit-centric code to Mozilla-centric code, and then futz around with the wonderful hell that is Internet Explorer. Until then, enjoy some of the theme designers best work I've seen on both Blogger and Posterous.