I've used Wrent A Wreck with no problems. Once I didn't have a credit card and my mother rented it for me, over the phone, and in another state too.
All they asked was that I bring a copy of her i.d. and a letter signed by her, saying it was okay for them to rent me the car under her name.
I had the car for a few days and had no problems with it at all.
wouldn't you just love to beeeeeeeeeee me? "-)