This looks like a GREAT piece of FREE software that will find blogs using some of the footprints above: (you must give email address).

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http://www.thefreeblogcommenter.com/

What's best about The Free Blog Commenter v2.0 v3.0 is that it is completely FREE

Quickly (couple minutes or so) find upto 60k blog posts per keyword entered.
Search KeywordLuv, CommentLuv, Nofollow Free and Top Comments blogs all at once
PR Check pages with single click
Multiple (Random) profile inputs support
Auto filling of profile on blog pages
Proxy and User Agent support
Select region of blogs that you wish to target
Use inbuilt browser or default browser to open blogs in
Saving / Loading of all settings and results.
Export to .txt file for use with common comment spammers
Threading for smooth usage
eBook to guide you through using the tool to its best
Lots more