The "Wayback Machine" is cool

The Wayback Machine lets you view old versions of web sites--for example, Yahoo as it looked in 1996.

Here's a description from the site:

"Browse through 30 billion web pages archived from 1996 to a few months ago. To start surfing the Wayback, type in the web address of a site or page where you would like to start, and press enter. Then select from the archived dates available. The resulting pages point to other archived pages at as close a date as possible. Keyword searching is not currently supported, but there are some researcher tools that perform similar functions (see the researcher tool section)."