Ingress
What I'd love to be able to do:
Get a list of portals within a polygon or within a defined distance from a point. (Not yet possible?)
Filter that list down to portals not yet hacked. (Not yet possible?)
Reverse geocode the lat/long to an address or street intersection.
Punch that in to http://routexl.com/ or http://www.plotaroute.com/
Print out the paper (to save on battery life and having to switch from a notes app).
Happy hacking!