OpenGTS

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.
To date, OpenGTS™ has been downloaded and put to use in over 110 countries around the world to track many 1000's of vehicles/assets around all 7 Continents. The types of vehicles and assets tracked include taxis, delivery vans, trucks/trailers, farm equipment, personal vehicles, service vehicles, containers, ships, ATVs, personal tracking, cell phones, and more.
While OpenGTS™ was designed to fill the needs of an entry-level fleet tracking system, it is also very highly configurable and scalable to larger enterprises as well.