Glympse - Glympse is the easy way to safely share your location in realtime. No sign-up needed.
a.placebetween.us - Find a meeting point based on place type
Zenly - Zenly is a GPS tracker to locate your friends in realtime.
OwnTracks - Cross-platform location sharing
Works For All - Find a central meeting place for everyone in the group
iOS - iOS is the operating system associated by default with all Apple mobile devices.