Most geographers look to OpenStreetMap for the data. It is indeed unique, with many attempts at duplicating the idea failed. At its core is crowdmapping: making regular people improve the map. Not having the data, geographers look into that too. Tempting idea, isn't it - engage a crowd into collecting data you need, not spending a cent on teaching and salaries. Have them walk around and collect building entrances for you! Why not make cyclists review cycling lanes? Everybody has phones, let them measure signal quality all over Estonia. We don't have yellow pages, but sure people could help building a POI dataset? At least pointing things on a map should be easy and draw in a crowd? We have seen many businesses toying with this, and many not-for-profit projects. Most failing. The Humanitarian OpenStreetMap Team still unmatched. Why does that happen? How do we ensure the data collected can be trusted? How do we get people to stay with us, and not leave after a few clicks? In this talk we'll look at a few past crowdmapping projects, learn what went well and what didn't, and derive a few pointers at how to get the data we need out of thin air (and people we don't know).