Open Street Map editor

JOSM is an editor for OpenStreetMap (http://www.openstreetmap.org) written in Java 1.6. The current version supports stand alone GPX tracks, GPX track data from the OSM database and existing nodes, line segments and metadata tags from the OSM database. Support for streets (called 'ways') is present too. It also provides:
* Ability to edit large sets of data.
* Offline support
* Photo<->GPS position support
* Changes/conflicts merging.

OpenStreetMap is a project aimed squarely at creating and providing free geographic data such as street maps to anyone who wants them.