You just found a cool spot and want to share it with the world;
is one tool.
The site works with Google maps, and users can plot their favorite places on the maps with photos and notes. Want to know where the libraries are in L.A.? Nightclubs in San Francisco? One of the better maps was "Stockholm, Sweden: A Frequent Visitor's Spots," by jnash.
The maps are only as good as the users who upload the information, and the details can be spotty or just plain wrong. I called up a map of Shanghai and got San Francisco instead.