I made my first small contributions to the OpenStreetMap project. I think making free maps is important and it’s a lot of fun. When you buy or use a proprietary map, it’s usually limited in its use, imperfect and you can’t customize and improve it. A free project can change this.
My first impressions about OpenStreetMap in Czech Republic are positive. A lot of work has already been done on it and it contains a lot of data. It’s still quite away from completeness of proprietary maps, many entities are missing and quality of data is variable. But we’ve already got reasonably complete data ready for further improvement. I think anybody can help a lot by improving areas he knows or visits, e.g. by adding missing tracks, names, points of interest and checking accuracy, correctness and completeness of current data. Great opportunity to spend a lot of time and fun outdoors, on trips and, of course, in front of a computer.
If you’d like to join, you should start with looking at OpenStreetMap Wiki.