I initially started working with Khoi Vinh, one of the most brilliant designers I know, a few years ago when we collaborated on a premium WordPress theme called Basic Maths. At the time, he was new to WordPress and was using Expression Engine to power his uber-popular blog. A few years later after seeing how malleable WordPress was, he asked me to help him reimagine his blog using WordPress as the backbone, and there was no way I could turn it down.
Khoi led the design while I did all of the WordPress development on the site. There are tons of nuggets of smart design and slick interaction techniques used throughout the site that you are simply better off seeing for yourself.