Glympse - Glympse is the easy way to safely share your location in realtime. No sign-up needed.
Foursquare - Foursquare is all about helping you find new ways to explore your city.
Zenly - Zenly is a GPS tracker to locate your friends in realtime.
Mapple.me - Mapple.me bridges the gap between available time and availability of friends to increase social...
OwnTracks - Cross-platform location sharing
LocationAPI - Instantly locate any device w/ WiFi, celltowers & IP address