I uploaded one of my psds. Learning rights only. It shows some basic techniques that I use. The main thing though is to start from just one layer. That one layer is duplicated constantly. All the effects layers are made from the first one. To get the effect, just use a filter. You'll have to figure out some of them yourself but some of them are easy enough. It's also got a really good colouring technique that I've used in all my sigs.
http://www.sendspace.com/file/n4e5ga