Making custom skins for your app

[Garrett Hylltun]

Gimp works fine if you're already familiar with larger graphic programs 
of this nature, and also it's easy on the wallet, as in open source.

Layers friendly, alpha channel and transparencies capable.  Plugins 
capable etc... Got just about everything you might need.

http://www.gimp.org/

I've been using it for years for just about all my graphic needs.  If I 
don't use that, I revert back to my ancient PaintShop Pro 5.? on Windows.

-Garrett