Wigle is an android app that scans for wireless networks and submits the data to a central database which is viewable to the public.
Flying Squirrel Wireless Discovery & Mapping Application
Flying Squirrel is a Government-off-the-Shelf (GOTS) software application developed by the U.S. Naval Research Laboratory to provide real-time discovery, analysis, and mapping of IEEE 802.11a/b/g/n wireless networks.
https://www.nrl.navy.mil/itd/chacs/5545/flying-squirrel/download (you need have the client certificate to download this)