A very cool web app called History Pin has popped up that tries to get some serious crowdsourcing going for linking old photos with Google Maps and even Streetview.  Check out the short video.



A few years back one of our our alums at Azavea helped made an interface like this for Philly with an unbelievable number of photos that they mapped at Philly History.
It is a shame that the two aren't merged, but maybe that will happen down the road.

h/t Chris P