Looking for ready tools to display real-time positions online

I found a solution asking the same question in Quora, and Ricardo gave me what I wanted: a simple solution that does not force me to spend time in devolpment or in system administration. The tool is Greenalp. You can add friends, adjust permissions, log data and view merged information from several users on a single map in real-time. We will use as tracker Android smartphone e the Greenalp Android app. We have just tested it this afternoon and it works.

OpenGTS™ ("Open GPS Tracking System") is the first available open source project designed specifically to provide web-based GPS tracking services for a "fleet" of vehicles.

http://opengts.sourceforge.net/

I haven't tried it myself yet, but it sounds like it should work out of the box.