Search party
You know that link Google gives you, offering pages “similar” to your search results? My website’s list of “similar pages” include, among other things, a whole bunch of musical artist sites: Rufus Wainwright, Fiona Apple, Coldplay, John Mayer, Elvis Costello, Weezer, and the White Stripes. Interesting. It’s begging me to figure out the degrees of separation. Well, let’s see, I’m set to open for Coldplay in Europe, and they… oh, wait, no. That can’t be right. I’ll have to start over. So, Rufus wrote a song for me, and I… oh, shush, you. Whose lazy-afternoon daydream is this, anyway?
At least some of the calculus must be based on the domain name. I tried feeding Google some blog pages hosted on LiveJournal and Xanga, and it just returned sites for other web publishing systems like Blogger and Diaryland.
Quick aside: I think the most underrated (and quietly unheralded) part of Google is the catalog search. I could look through those all day.