I like the fact that anybody can comment on my blog posts. One option is therefore to comment under the "Anonymous" option, and I don't want to eliminate that option. A problem arises, however, when readers confront numerous "Anonymous" comments, often in the same combox, and would like some way of distinguishing their authors from one another.
My suggestion is that readers pick the "Name/URL" option and either state their personal name or pick a moniker and stick with it (the URL is optional). That way commentators will have consistent identities to work with, and it will be easier for participants to track combox discussions and continue their conversations from one combox to the next.