OpenStreetMap.org is like wikipedia but for maps, you can add anything you like and help make a free map of the world.
Mapping parties are community events targeted at getting a specific area mapped in a day or a weekend. You come along, are loaned a GPS unit and shown how to use it (it's easy!) and you go out mapping an area of your choosing. Then you come back and are shown how to get that data in to the map.
Official Website: http://wiki.openstreetmap.org/index.php/Chicago
Added by mappingparty on September 9, 2008
mappingparty2
Rain date? No way! Don't let a little rain worry you. Bring your laptop, Panera has wireless. If we can't get out and map on foot we will.
Have a mapper meet and greet.
Have an editor coaching session.
Have an introduction to OpenStreetMap for curious newcomers.
And do some on-line editing.
So come on out, even if it is raining!