The French NOE biodiversity preservation program has put in place a collaborative programme for monitoring biodiversity of butterflies in gardens. In 2006, close to 15000 persons have collected and transmitted observation data over the Internet. This led to a set of observations on the geographic and temporal distribution of 28 species that could never have been collected by classical scientific data collection.
This is but one example among probably hundreds of using the distributed abilities of people for achieving a task of common interest, all the more remarkable because in this case, the task accomplished by individuals required some non-trivial observation abilities. Feel free to mention other cases as comments to this post.