I used one module as a garage server. It is an access point and waits for an "OPEN" command. It has a connection to a magnetic reed sensor (or microswitch) to check if the garage door is closed. To open the door, it closes the contacts on the garage door button for a couple of seconds. This can be via relay or an optoisolator.
I have another module on each car. This module is a client and continually tries to bind to the server. When bound, it sends an "OPEN" command to the server. So when you are driving home and approach your house, this module will bind to the garage module and open your garage door automatically!
This is so good that it can probably be commercialized or even launch on Kickstarter !