Architecting CSS: This is a pretty shallow, but solid, article on how to organize CSS. It covers how to organizes the three big components of CSS.
There’s some good advice there, but I’m really looking for something a bit more in-depth. This is a problem you run into more and more as your applications get bigger and bigger. CSS bugs get harder and harder to track down.
Thanks to David for pointing out this article in a comment to my post on CSSTidy.