Loopt on Your Mobile
Loopt is a new location-based social mapping service that installs directly on your mobile phone. Using the service, you can share your location and send messages and photos with your friends. You can also see who's close. Giz describes, "Loopt automatically updates the location of everyone in a private network and displays that information directly on a map on the phone. It even sends an alert when a friend in the network is near, putting an end to missed connections in the mall, at the movies or around town."