Zenly - Zenly is a GPS tracker to locate your friends in realtime.
Glympse - Glympse is the easy way to safely share your location in realtime. No sign-up needed.
Touch GIS - The premier tool for mobile field data collection and visualization. Available for iPhone & iPad.
LockOnMe - LockOnMe is a location-sharing app, displaying targets and associated Points Of Interest on maps & fun radars.
Cone - A delightful and easy to use color picker for the real world
OwnTracks - Cross-platform location sharing