We were quoted $50 for new garage door openers. We already had one door opener, so for the same price we went about building our own network enabled garage door opener with an arduino. Members could open the garage door using an android app on their mobile phones, or by typing their unique pin numbers into a special website. The door status is logged to a mysql server and pushed to other mobile devices so we could see when someone had opened (or closed) the door.
Here's the initial prototype (that we used for about 5 months before soldering it up) was just a relay connected to the existing door opener, and a reed switch connected to the door to provide feedback when it actually opens.
Recently we got our RFID reader working in tandem with the existing door opener.
This all links back to an off site mysql/php setup here where we can see door history: http://gctechspace.org/door/
Was fun to create and I cannot wait to print a case for all this on the reprap.