Sometimes you need to draw upon years of experience working on cars if you want to fix a computer. Usually, times like these end when you're straddling a ruined iMac with a five pound sledge in your hands. However, I recently brought the worlds of automotive repair and computers together with positive results.
Lauren's computer was in need of an overhaul, so I offered to re-install Windows and give her an Ubuntu Linux partition to play with. The only problem was getting all of her data off the computer before I wiped it.
Time for good news/bad news - we had an external drive, but my father accidentally threw the AC adapter away with a bunch of old cell phone chargers. None of the adapters we had in the house would match the 12V at 2A needed by the drive, and nothing in the local Radio Shack could do it, either.
So, I started thinking like a shadetree mechanic. "What would happen if I hooked it up to a car battery?"
With some help from Spencer at Radio Shack, I had a rig that should work. From the battery terminals, power went to a cigatette lighter plug. a 12V 2A power supply plugged into that, and ended in the proper plug to go into the hard drive. With some trepidation, I hooked everything up, and hit the button. It worked!