From Instructables user stangtime comes a video showing how an old computer power supply can be repurposed.
"Old computer power supplies are a great resource for ham radio gear, CB radios, chargers, or any other item that needs a regulated 12 volt source. Many of these older power supplies do not have an on/off switch on the unit. By tapping the green wire and any of the black wires on that connection plug that goes to the motherboard a standard switch can be wired in."
I think my favorite part of the video is the last sentence, "So reuse these things, don't just pitch 'em." Sums it up for pretty much every gadget that cycles through our lives.