Blogdex has informally announced a new feature called the "social network explorer." The URL format is like this:

http://blogdex.media.mit.edu/socnet/index.asp?ego=domain.tld

where domain.tld is the site you want to know about (such as memestreams.net, which probably isn't in the blogdex database).

It displays your selected site in the top 3/4 of the screen. The bottom 1/4 is split into three frames containing relationships for the selected site: "linked to", "friends", and "links to". The "friends" panel is the interesting one ... the others are just simple SELECT queries on the database. Check it out, recalling that the authors say it's still in testing.