A few months ago, I posted about HistoryPin.com, where you can compare vintage photographs of locations with current views from Google.
Now there's a similar site called WhatWasThere. Their About section says:
The WhatWasThere project was inspired by the realization that we could leverage technology and the connections it facilitates to provide a new human experience of time and space – a virtual time machine of sorts that allows users to navigate familiar streets as they appeared in the past.For more about this project, contact them at firstname.lastname@example.org.
The premise is simple: provide a platform where anyone can easily upload a photograph with two straightforward tags to provide context: Location and Year. If enough people upload enough photographs in enough places, together we will weave together a photographic history of the world (or at least any place covered by Google Maps). So wherever you are in the world, take a moment to upload a photograph and contribute to history!