Navizon is a software-only positioning system that works with Wi-Fi and or cellular signals. That’s right, GPS is not required! Essentially, Navizon works as a virtual GPS by triangulating your position using signals received from Wi-Fi access points and cellular towers.
At the heart of the system is a peer-to-peer database that covers metropolitan areas in the US and Europe. The data is gathered by users who do have GPS and collect, use and store GPS location data on their devices and feed that information back to the Navizon Global Network. When a non-GPS user tries to find out where he is, the data he collects is matched up against the database to come up with his location.
Navizon is free for non-commercial use and works with any phone or PDA running a Windows Mobile platform.
Thanks to Emily261 for the tip!