Jack Balkin (Yale) has finally had to pull comments on his fine blog.  "Above the Law"–whose comments sections are a cesspool of juvenile nonsense, misogyny and racism rivalling Autoadmit–isn't really cleaning things up, just trying to hide it a bit more.  Orin Kerr (George Washington) comments on his efforts to maintain a worthwhile "comments" culture on his blog postings.  My own comments policy is here.  At my philosophy blog, where I have the same policy but open comments more often, the approach has been quite popular with readers; as one wrote: 

The vast majority of discussion on the internet is worthless, your blog being a rare exception. If comments are not moderated it is safe to assume not only that there will be more junk comments, but that this decrease in average quality will cause a decrease in the number of worthwhile comments as well. Many of the most informative and best-considered comments in current discussions come from well-respected, and no doubt very busy, philosophers, whom I imagine would have little desire to spend their scant free time engaging with belligerent internet trolls.