So here's one way to use these old supplies. I did this today because my current bench supply bit the dust (it was only good for 1A anyway).
http://www.chesterfamily.org/gallery/ProjectsAndStuff/IMG_1531.jpg.html
and
http://www.chesterfamily.org/gallery/ProjectsAndStuff/IMG_1532.jpg.html
I spent a grand total of around $3 on this for the 12 awg wire. The rest I already had. The power switch came from the same server the supply came from.
This unit gives me +12V, +5V, +3.3V and -12V DC - PERFECT for Arduino projects. 