Ryo Chijiiwa's BlogMatcher will take a weblog's URL as input, perform a link analysis, and produce an ordered list of weblogs that feature a similar set of links. This is a pretty neat tool for matching people with similar tastes - in my view a very relevant problem, as the expanding blogosphere is full of people who ought to know one another.

Similarly to Google, this service demonstrates the unforeseen benefits that can be derived from many individual people's linking activity. (Read the FAQ if you're curious to know how it works.)