The folks at Bostonography provide an update on their efforts to crowdsource the neighborhoods of Boston. They offer a nice analysis of different levels of agreement in the about 300 responses to freely draw polygons on their interactive map.
WAMU has teamed up with Transportation Nation to map all of the abandoned bicycles in D.C., and they need your help. If you happen upon a sad bicycle that's missing some parts and doesn't look like it'll be recovered anytime soon, email a picture to bikes (at) wamu (dot) org and they'll add it to their map.
I guess anyone could look at the map and collect the derelict bikes for their own use.
The Global Health Program at the Council on Foreign Relations has been tracking news reports since 2008 to produce an interactive map that plots global outbreaks of diseases that are easily prevented by inexpensive and effective vaccines. These diseases include measles, mumps, whooping cough, polio, and rubella.