In terms of aggregators don't forget about the Google Reader which apparently is kicking Bloglines' butt.

http://www.techcrunch.com/2007/01/19/just-how-big-is-google-reader/
http://www.techcrunch.com/2007/02/22/feedburner-releases-major-user-engagement-report/

Sincerely,
Ben

Ben Watson (ben.watson@thomson.com)
VP of Collaboration, Thomson NETg