I thought people in here would find this interesting.
The goal of the project OpenStreetMap is to collect cartographic data worldwide.
From ZDNet UK - "Data is gathered by contributors walking, driving, cycling or otherwise making their way along streets, paths or other features, with a GPS receiver recording their every move. The breadcrumb trails generated in this way are then used to trace the points and paths needed to create a map."
Also, "today it uses Ruby on Rails, backed by a MySQL database. Maps are drawn using either an existing open-source renderer called Mapnik, or a home-grown SVG-based renderer, Osmarender. Both of these are displayed on the OpenStreetMap website using an Ajax "slippy map" implementation called "OpenLayers"."
Articles - Features on ZDNet UK