play with BlogPulse
If you have not done this yet, spend some time playing with blogpulse (from Nielson BuzzMetrics). Whlle other web and social media measurement companies - such as m:metrics and Big Champaign - give you only little samples, saving their tools for paying customers, BlogPulse (at least for now) actually allows you to do some pretty impressive research. Try each of four BlogPulse tools.