Clusty is a great clustering engine, at least for my uses. It clusters a whole lot more than blogs, so have your fun trying the other tabs. This is something that Raul Valdes-Perez at Carnegie Mellon has put together. He was a student of the late Herbert Simon.
It seems a bit slow, I have not compared it with others. What is your experience with it?
update: I am having some sort of trouble between Blogger and ecto, and I can not quite figure out which one is acting up. I have had posts disapper from blogger that I made with ecto, and somehow the web dashboard on blogger and my ecto are not in sync. This never happened before, but there is always a first. When I update a post from ecto the result on blogger seems unpredictable…
update 2 (06.02.06 Mon) Blogger and ecto are on speaking terms here. What goes on beyond my screen and router is often a mystery to me.