Want to see the old Google -- probably before half of you were born searching? Check out Google's search engine from 2001, and what Google calls its oldest available index. You'll probably notice that Gmail back in 2001 was a Gnome-based Linux mail client and that YouTube didn't exist. Searching for Barry Schwartz back in 2001 brings back some psychology dude who must've written a book (joking aside, I own the book). Searching for Tamar Weinberg yields no results of the present Tamar Weinberg, but that's probably because I didn't get married (and didn't change my last name) until 2005. However, you can dig up relevant information by searching with my old name, so I consider this pretty accurate for 2001.
Besides that, though, those searching reflect back on a day when Google wasn't dominated by ads and when their rankings (#1) were easier to achieve. Further, it seems that some are trying to leverage this old search engine for competitive research.
Forum discussion continues at WebmasterWorld and DigitalPoint Forums.