I too have never really gotten the concept on how to do my own CSS. I'm actually surprised there isn't a shop for CSS either, but then again, maybe no one really thinnks they are needed [not sure]. I'd like to learn one of these days, but I'm satisfied at what I can do now. I have to admit though, with CSS a graphic banner or signature can really outshine itself.
By the way, The Incredible Wandering Thread has now gained a total of 1000 posts :).