Facebook Places - Let your friends help you discover restaurants, hotels, museums and more.
Glympse - Glympse is the easy way to safely share your location in realtime. No sign-up needed.
TransforMap - There are Plenty of Alternatives. TransforMap makes them visible.
Zenly - Zenly is a GPS tracker to locate your friends in realtime.
LockOnMe - LockOnMe is a location-sharing app, displaying targets and associated Points Of Interest on maps & fun radars.
OwnTracks - Cross-platform location sharing