Friendz - Friendz is a free GPS based app that lets you find your groups on the map & keeps you notified.
Glympse - Glympse is the easy way to safely share your location in realtime. No sign-up needed.
Pathshare - Pathshare is a beautiful app that helps you share your path in realtime.
Facebook Places - Let your friends help you discover restaurants, hotels, museums and more.
Foursquare - Foursquare is all about helping you find new ways to explore your city.
TransforMap - There are Plenty of Alternatives. TransforMap makes them visible.