steven Levitt, author of Freakonomics, is having a problem on his blog with people who post annoying comments.
Here's what I said to him:
Yes of course you should ban anonymous comments. Registration is free and easy, and it ensures the legitimacy of anyone motivated enough to respond.
You might check into the "trackback" feature available on many blog sites. People's comments appear on their own sites, not yours, but anyone can still read and respond by doing a simple search for comments to your original post. That way you can still get the feedback you want from the world at large while ignoring the obnoxious posters