The nation skins for A&A were one of my most favorite projects.  I modeled and textured each UI skin in 3DMax, so that the straight renders could go into the game without having to tweak in photoshop.  This was because of the many versions we had to have to support different screen resolutions.  At one time the buttons and knobs animated, and I had a maxscript and photoshop action combo running to output all the frames.