I had fun making this minimal, responsive Jekyll theme. It's somewhat inspired by the original minimal theme for Github Pages, but a bit more suitable for blogging. I've made it available on Github here.
I was going to write a post about the experience of setting the site up on Rackspace, as I did hit a few snags, but then I came across this excellent post by Philip Thomas, which covers everything you need to know.
The one major caveat revolves around the need to purge index files from the CDN, so look out for that if you decide to go the Rackspace route.