OpenStreetMap founded in 2004 by Steve Coast. It was originally for mapping the UK because of copyright restrictions on government-created data.
OpenStreetMap is open data: you are free to use it for any purpose as long as you credit OpenStreetMap and its contributors.
Has over 1,000,000 registered users. Over 21 million miles of road data. Over 113 million buildings.
Register at http://www.openstreetmap.org/
Click Edit to start editing!
Learn about OSM at http://learnosm.org/en/
Near real-time visualization of edits to OSM: http://osmlab.github.io/show-me-the-way/
Complete map-fixing challenges at MapRoulette http://maproulette.org
OSM Data Report (2013): https://www.mapbox.com/osm-data-report/
Interesting data about tags: http://taginfo.openstreetmap.org/
Report about Austin area edits: http://www.itoworld.com/product/osm/map?area=7673:0&style=None