In the interest of upping the number of themes in the registry, I spent a few hours today creating a theme in the style of the community site. For my first attempt at theming, I found it quite straightforward (although it's 90% Vanilla code).

Demo: http://code.taylortom.co.uk/examples/adapt-theme-community/
Code: https://github.com/taylortom/adapt-theme-community

I've put some details on reusable styles in the README, so have a look in there before using.

p.s. Everything was thrown together quite quickly, so in the likely event that you find an issue, let me know on GitHub (or maybe even submit a PR if you're so inclined!).

p.p.s. It's also been tested in the authoring tool (for those that use it).