Hi, i'm throwing this out there for chez hack. I can do ios mobile location based stuff, a very simple app that's hooked up to a web dashboard that would be great for mapping out hacker spaces or neighborhoods through geofencing.

It also has image recognition that's better than QR codes, that would recognize a photograph.

it's using a commercial SDK though (Qualcomm's Gimbal) so that's the caveat... but I think if anyone's down for interesting ideas with that, it would be a fun project!