It's quite a challenge to find out how many blogs and bloggers are out there. Let's see... (figures fresh from today when available)

• Technorati: 5,790,155 weblogs watched
• BSentinel: 502,679 weblogs counted (come on Stéphane, you can do better than that! ;-) )
• NITLE Blog Census: 2,108,226 visited sites we think are weblogs
• PEW Internet & American Life Project: (report) 8 million American adults say they have created blogs
• LiveJournal stats: Total accounts: 5,703,540... active in some way: 2,460,062
• Skyblog (France): 1,358,564 Skyblogs
• The Blog Herald: Blog numbers are closer to 34.5 million wordwide

Compare this to the January 2005 Netcraft Web Survey: 58,194,836 sites and 26,405,729 active sites. (Before you mention it, according to their methodology, Netcraft would see all domains such as LiveJournal.com and TypePad's blogs.com as one site, because of their focus on domain names and web servers.)

I know it's difficult to draw the line between a blog and a personal site, it's even more difficult to split active vs. inactive blogs (I contend that a blog which hasn't been updated in a while is inactive, unless you forget about its visitors activity and the value of archived content). I'm doubtful about most americano-centric tools which are not following very well what's out of the Anglo-Saxon blogosphere. I find Technorati's figures dubious -- e.g. Zeldman would probably not define his site as a blog, Adaptive Path has a site that uses MT as a CMS and my corporate Capgemini site is certainly not a blog, but those three are in Technorati's index (how does Technorati count blogs, what is their methodology? Same questions for all other indexes.) May be the Blog Herald is closer to the truth, however if you match their figures with the (unsubstantiated) figure of 70 million web sites that I keep seeing or hearing here and there, that would mean that half the sites are blogs. It doesn't make sense.

Do you know of other sources to refine those figures?