The AC compressor in my mom's old car had the clutch fall apart (strangest failure I'd ever seen--the compressor didn't lock up, the clutch just fell apart), so there was no putting a new belt on without fixing the AC compressor. It was also 40 miles away from my trusted mechanic.
Since the water pump on that engine is driven by the timing belt, I just grabbed the battery out of my other car, put it in a bucket so it didn't mess up the carpet, and wired it up to a cigarette lighter cord and a multimeter. I started the engine and plugged the cigarette lighter cord in, so as to back-feed power from the 2nd battery through the cigarette lighter socket (so it was running on two batteries in parallel).
I drove it the 40 miles with no power steering and no alternator, watching the battery slowly discharge on the multimeter. When I got there, as I recall it had enough charge to go for probably another hour.