The WhatWasThere project
is a virtual time machine that ties historical photos to Google Maps, and allows you to tour familiar streets to see how they appeared in the past.
Anyone can participate in this project. You can easily upload a photo with two straightforward tags to provide context: Location and Year. If enough people upload enough places, the project will weave together a photographic history of the world (or, at least any place currently covered by Google Maps).
It's a fascinating idea. I may even have to start posting some photos of Brillion!
Take a peek. Visit the above link, type in your city or state, and start searching location photos from the past. You never know what you might find.