Search for web pages that may have expired

I ran across this site earlier this month when the paper was putting together a big package about the Harrisburg Incinerator. 

We were looking for photos and information on a company involved in the project, dating back to 2003-2004.

And someone sent us this site, called Internet Archive Wayback Machine.

You have to search on a web address, but then you get a list of links to that page by year.  It is totally cool, and could be an important research tool for newspapers. 

A few years back, we looked at some web sites that had changed because of 9-11, but I remember that it was difficult to illustrate the before-look of the pages.