If you don't already know about it, you should check out the KnobMan software for generating beautiful GUI controls. Almost all of the GUI controls that ship with v6.5 were developed with it and downloaded from the excellent Gallery where users upload new GUI controls on a regular basis.

KnobMan:
http://www.g200kg.com/en/softw.....obman.html

Gallery of Controls:
http://www.g200kg.com/en/webkn.....allery.php

SkinMan:
There is another free product from the same site that makes skins for backgrounds with a variety of Photoshop-esque effects. Works great with KnobMan and you can import knob images in as a rough guide to check your skinning:
http://www.g200kg.com/en/softw.....inman.html

SkinMan Demo:

Video Tutorial on making the SSL Knob:

Detailed Video Tutorial on making knob controls; starts at 3:30 and goes to about 19:00:

Another knob Video Tutorial: