I have had mixed things to say about Avvo in the past: Avvo's Online Ratings For Lawyers Come To Boston and Avvo Revisited - I am a 23% Better Lawyer.
Avvo put together a great list of the Top Legal Blogs.
Rather than using the voodoo used by the ABA, Avvo used the blogs Alexa ranking. Alexa computes traffic rankings by analyzing the Web usage of millions of Alexa Toolbar users and data obtained from other, diverse traffic data sources. The Alexa information may be off because it relies on information from its toolbar users. I wonder how many lawyers have the toolbar installed. (I did not install it until I saw the blog list.) So there are a few oddballs in the list. But there is a great transparency to the list that I have not seen in other legal blog listings.
Sadly KM space does not make the top 100 with an Alexa ranking of only 1,319,459.
You can certainly argue that Alexa is not a useful tool for measuring traffic and ranking site (as I pointed out). The ranking shows the popularity of these blogs to Alexa users. You can interpret whether this carries over to a different population of lawyers and those in the legal field.
As Brian Leiter argues on his Law School reports blog, even site visitors and page views do not capture the best statistic. He points out that average site visit time should be factored into the number site visits to measure impact.
You also should look at the number of subscribers and incoming links to a site. I have yet to see an effective way to mash this all together in a meaningful way.