PlaceTrack location sharing (formerly Latitude updater)

PlaceTrack is the best full-featured location sharing app available to date. Initially created as a background Google Latitude updater, PlaceTrack now uses its own backend infrastructure and continues to work well with even more sharing features. Your location data can now include location history, speed, altitude, whether you’re walking, running, moving in a vehicle or resting (using the new M7 coprocessor on supported devices).
PlaceTrack can also optionally share live location data through secret web urls: you can authorize anyone with web access to see where you are or where you have been.

MAIN FEATURES
- excellent battery usage: PlaceTrack uses SLC mode (Significant Location Change) and region monitoring, NOT continuous background. PlaceTrack is suspended in the background most of the time and is woken up only when you move significantly (detected using cell towers signal); most of the time it just sleeps and the GPS hardware is powered off to preserve battery
- save your location history for later viewing
- optionally share your live location or location history with authorized PlaceTrack contacts (or automatically publish to secret web urls for web sharing)
- forced contact location updates: you can ask for a location update from a contact and the backend platform will use new iOS7 features to silently ask your contact device for a new location update
- delayed sync: stores your locations when network is unreachable and pushes them to the PlaceTrack servers when you're back online
- Foursquare and Facebook support: see your friends' checkins on the map
- Check In and Auto Check In support (to Foursquare and Facebook). Auto Check-In uses iOS geofencing.
- server side location history: when you upgrade from older versions, local on-device history will be pushed to the server and then removed. A comprehensive web interface for location history management will be provided later.
- location sharing on Twitter, SMS, Email, Facebook
- in-app streetview images for friends’ location. Foursquare photos for Foursquare checkins (if available) 
- location sharing works using address book phone numbers: your phone number is authenticated through an sms code on your first activation
- your data, including your phone number and location, is always sent on a secure connection (ssl) and is never shared with any third party