A few weeks ago I wrote about Ming and Michael's ideas on personalized collaborative filtering in a post called "Recommender systems and the microblogosphere". The idea being that there are blogospheres around each weblog reader, and that my "sphere of trust" - the set of people I'm likely to take seriously - roughly corresponds to people who are a few degrees of separation from me. And that I might be interested in knowing what those people think of a certain idea/thing/person in addition to knowing what Google thinks.
Now (via Alex) I found Micah Alpern's microblogosphere search tool, which implements the case N=1. I haven't had time to try it yet but it looks like it might be very useful.