I would've done this myself, but don't have access to enough of the information. Maybe this is even two articles.
What I'd like to see is a definitive piece on the various aggregators and a comparision of the number of blogs they include, features, etc. for purposes of making an informed decision when choosing a primary aggregator. There are a lot of different ways people use their aggregators, and while right now I get what I need from Bloglines, if my needs change, maybe there's something better for a different kind of purpose. I'd like to be able to easily and quickly figure this out.
When it comes to tracking a specific subject or news item, I'm running into some difficulty. So far, neither Feedster nor Technorati has given me results that actually relate to my query. So I'd like to see something that imstructs on the best way of using all this stuff with a minimum of frustration!