Life360, MapTrack? (pay), Zemango, Find my Friends, Yougy, Hemisphere, Family by Sygic, https://openpaths.cc/, Glympse, swarmly, Chronos (?), Google+,
there's also lost phone appS: AndroidLost?, where's my droid, Puntalo,
i guess for me the list of feasible candidates, in descending order of popularity on Android Market:
Life360, Family by Sygic, Find my Friends nliteapps, MapTrack? (pay),
https://play.google.com/store/apps/details?id=com.life360.android.safetymapd
heard that it has a 6 person limit
https://play.google.com/store/apps/details?id=com.sygic.familywhere.android
crashed for me. perhaps because it got stuck in 'augmented reality' mode, and my camera is broken and crashes apps that try to access it.
i rebooted then it worked. seems like a simpler version of life360.
seems good but confusing interface, so i guess i can't recommend it to non-nerdy friends who might get frustrated.
the UI is a little slow.
https://play.google.com/store/apps/details?id=com.vistechprojects.maptrack
also saves location history
i'd be willing to pay $3 but i dunno if i'd be able to convice anyone else to...
https://play.google.com/store/apps/details?id=com.fourpg.nomad
also saves location history, but i think it locks location precision to 10 feet while recording, which probably uses a lot of battery
needed to turn sharing on manually after reboot
https://play.google.com/store/apps/details?id=com.howettl.hemisphere
not compatible with my old phone
seems to be an alias for Life360 (!?!)
as of this writing, not available yet
has 'auto-respond to update location requests' option
heard that you have to constantly send requests or queries
didn't try it but i don't see a share with friends option in the description
heard that it has too many social features
i tried Google+ Locations first but my wife hit the bug described by JoAnn? Brereton on this page: https://plus.google.com/+GoogleMaps/posts/D4HkuvisrPY
found a fix at http://www.pocketables.com/2013/07/root-user-fix-for-google-locations-blank-tilesmissing-maps.html (or https://plus.google.com/109052420587654093130/posts/Rzg2aL4wpi5 ) but it requires a rooted phone and she has a stock install.