In honor of Google's tenth birthday*, the search engine has posted a version of itself as it appeared in January 2001 (the earliest available index). It was a simpler time: only 1,326,920,000 web pages were in the index. Today it's over 8 billion, though Google stopped revealing the exact number in 2005, saying the index size was "meaningless." Doing a search on the 2001-era index reveals how much the web has changed since then. For one thing, there's no mental_floss blog! There is a mention of the magazine in a Duke Chronicle piece, though the link itself is broken. (We'd have to wait for roughly August 2002 to see a mental_floss web presence.) Searches for today's staple websites like Flickr, Twitter, and Digg turn up lots of interesting results, but of course the services themselves didn't exist yet.
Because the index is so old, many links are broken. Google has helpfully included a link on each search result to "View old version on the Internet Archive," which looks up that page on the Wayback Machine. (By the way, if you're unfamiliar with the Wayback Machine or Archive.org, please read this -- it's an amazing resource for all net users.)
Go search for yourself and see how things have changed in seven years. Note that the index will only be available for one month, so get it while it's, uh, hot and very stale?
* = There's some debate about when Google's birthdate actually was. Everyone agrees that it was in September 1998, but Google's not saying which day it was. A testament to Google's awesomeness: they celebrate "depending on when people feel like having cake."