GSM-Tracker is a user supported, free, global location service for GSM users. GSM-Tracker can help you locate your current geographical position, and other useful information about your current location. If your location is not yet added to the developer's database, you can be the first to describe it, and help them extend this service.
Users who contribute with information on more then 100 new cells, are rewarded with free software for their mobile phones! A great deal for a handy piece of software.