Found this via another site.  It uses the number of sites linking to your blog to calculate a value for that blog.  (I guess my IPO will be a bit longer in the making. LibrarianActivist on the other hand... )

Head Tale


        My blog is worth $7,339.02.
How much is your blog worth?


LibrarianActivist.org


        My blog is worth $11,290.80.
How much is your blog worth?