Remote volunteers (you) trace satellite imagery to create maps. Each project has different requirements, for example you may need to trace round buildings, mark roads or outline residential areas. Once verified, community volunteers can add local detail such as road names and building use. The humanitarian organisations like Red Cross and Doctors Without Borders can use the maps for planning disaster response or longer term projects such as elimination of disease.
You will need to create an account with open street map and watch a couple of videos to learn how to map, but after that, you can do something meaningful in 10 minutes. Each area requiring mapping is divided into squares, and you can do as much or as little as you want within each square.