"Flawed satnav instructions are the scapegoat for ridiculous round-trips, buses wedged under bridges, and ambulances taking life-threatening diversions. But few understand or appreciate how far mapping companies go to ensure the accuracy of the data they’re providing."
Open.mapquest.com uses OpenStreetMap (previously, -er, -erer, -est) data served through MapQuest's own server, and any edits feed back into the main OpenStreetMap database. [more inside]
OpenStreetMap is a free editable map of the whole world, using uploaded GPS traces. So far: London and several other cities have been mapped. (via dataisnature)
Give a group of Amsterdamers a GPS tracking device for a couple of months, plot their movements over a black background, and the resulting traces map the city through the movements of its inhabitants. Alternately, make your own GPS art, or play GPS Hide and Seek.