Open Street Map is a community based projects with the aim of providing a free world map. In many areas the coverage is pretty good, even exceeding commercial maps. Some days ago I stumpled apon some really cool java me application called GPSMid, which utilizes this map data on the mobile phone.
You may connect to a bluetooth gps device. Afterwards your current position will be shown on the device. Even routing is possible. All that is needed is a Java ME capable mobile phone.