Des Plaines, IL
My alternator broke down right after I parked at O'Hare airport, and I took my flight. Before my flight back to Chicago, I called these guys up and described the problem. When I landed, they were waiting at my car before I got there! After around an hour, they had put in a new alternator and I was ready to go. Without them, I would have had to get my car towed to a mechanic and have it fixed the next day (it was late evening). They saved all the towing and the tension.
I think they provide a very useful service by coming over and fixing a car even at times when other shops have closed down.