I've been doing research on automatic garage door closers as well. Here is the company I think I'll go with...
http://www.autocloser.com/
They also make a model/unit called the Doorminder, which is worth a look.
I had my eye on either the Autocloser or the Doorminder, both available here..
http://www.autocloser.com/products.asp
The Doorminder uses a second set of sensors and can close a door in as little as 15 seconds after the vehicle clears the door. -Probably good for downtown condo garages, and...