You’ve heard of Wikipedia, now there’s Wikimapia:
http://www.wikimapia.org
This site uses google earth to display satellite photos, and just as wikipedia allows people to post and edit articles, wikimapia allows anyone to add a point of interest on the map along with a description, or edit an existing POI. For example, when I zoom in centered on Miller Park in Milwaukee, I see a wide variety of entries including State Fair Park, The Domes, a cemetary, K-mart, Marquette University with each building labeled, and of course, “Cool Places to Get Drunk After a Brewer’s Game”.
Not sure how useful this is, but still kinda cool. Maybe as more POI’s are added it will be more useful, but then at some point I think they’ll have to add filtering (don’t see any yet).