Open Street Map
OpenStreetMap is a free editable map of the whole world, made by people recording GPS tracks and editing map data.

Free The PostCode
Free The Postcode is a project similar to Open Postcode DataBase, it aims to build a postcode to latitude/longitude file from user submitted postcodes and GPS coordinates.

New Popular Edition Maps
NPEMaps is a project that aims to gather UK postcode to latitude/longitude data by getting visitors to submit postcodes based on out of copyright 1940's maps.

Working on a geodata, geographic or otherwise related project? Then let us know about it!