It's just about here - we're hosting the first Washington, DC area mapping party this weekend at the FortiusOne office in Arlington. You can also meet the GeoCommons team!
If you haven't been to a mapping party - essentially anyone can show up throughout the day, borrow a GPS unit (or bring your own), get a quick tutorial on how to collect data for OpenStreetMap and then head out for a gorgeous day around the town gathering tracks, points of interest, road data, bike trails, walking areas, etc. It's a great way to explore the city and also make maps that are useful to you! While the OSM map for Arlington and DC "looks" fairly complete it's missing a lot of useful information such as directions, metros and more - so it still needs a lot of TLC.
Once you get back with your data we can show you how to upload it to OpenStreetMap. Of course, there is also typically post-mapping socializing somewhere nearby. Overall the day is very free and you can come for as short as an hour or two - but I'll warn you that it's very addictive.
The event is listed for both Saturday and Sunday - but my recommendation is to come on Sunday. Saturday is SocialDevCamp East up in Baltimore, and also on Sunday Mikel will be in town to provide his mapping expertise to the party.
Here are the event details (in hCal of course).
November 1 or 2, approximately 10-5PM at the FortiusOne Office