"When I wanted a remote garage door so I could just ride up on my motorcycle, I couldn't find "any kind of remote Wifi/GSM-activated thing" so I have a Raspberry Pi that my phone talks to over the cell connection when the GPS says I'm near home. I made damned sure to make it TLS-encrypted though, so no-one can snoop my fairly simple protocol, and my phone presents the certificate for authorization."
Patented that? Sounds like you actually have a good idea for Kickstarter, or at least a good opportunity for some karma points by publishing the instructions...