I stumbled upon this video by Phil Levchenko showing how to turn an ATX power supply into a bench power supply. I had an old PSU laying around and thought this would be a perfect way to give it a new life. Phil's video is great, but I found the video tutorial format a bit tricky to follow at times.
Click through for some pictures, tips and diagrams that you may find helpful.
Standard ATX wire colours...
When I started tearing down the PSU I was tempted to start de-soldering all those extra red, yellow, orange, and black wires. Twisting them together and routing them to binding posts seemed like too much of a pain. Then I realized that these PSUs are capable of providing a pretty significant amount of current (~20 Amps on 5v rail)! The wires in my power supply are 18 AWG, and I couldn't find a definitive answer to how much current a single wire could safely carry. So in the end I kept 6 wires per colour... just to be safe.
In my PSU I chose to pull out +12v, +5v, and +3.3v to binding posts since I can't imagine a use for -12v or -5v.