Some smart people from the University of Maryland created a site called Feeds That Matter that use an algorigthm to determine the top blogs in various categories. They also wrote a research paper on the algorithm, which uses Bloglines data. The paper itself is the most interesting part of this project.
http://ebiquity.umbc.edu/_file_directory_/papers/290.pdf
There research indicates that nearly half of the feeds in Bloglines are from the Blospot.com domain. In contrast nearly half of the feeds in Blogpulse are from the livejournal.com domain and Blogspot.com ranks only 4th. Different datasets indeed.
Looking more closely at the Feeds That Matter website, I selected the RSS category to determine how well their algorighm actually ranks blogs. The top two feeds in RSS were Lockergnome's RSS and Atom tips and Webloginc's The RSS Weblog. Lockergnome's site is an ad infested blog with little original content, mostly quoted content from other blogs, few reader comments, few inbound links and sporadic life. The Webloginc blog was recently shutdown and has been dormant for six months. Bloglines homepage ranks 4, which doesn't make much sense at all. Dave Winer's RSS Blog ranks 6 and has been offline for many months. Many of the other top feeds are also barely active or dormant. They should add a component to their algorithm that includes recent activity.
Thanks to Scott Kingery for the link and for playing tag with me.
Thanks,
Randy