Two opinions from a WordPress user and occasional Blogger dabbler:

  1. Allow anyone to comment: I understand that turning off anonymous comments looks attractive when you first install Blogger, but what it really means is ‘Don’t allow comments from anyone who isn’t registered with Blogger‘. That’s right, selecting this option means people can’t comment on your blog without signing up for a Blogger or Gmail account, and even if they have one of them they can’t leave their non-blogger URL in your comment. I have two main blogs, that I like to leave in comments, and I like to choose between them depending on the subject of the blog I’m commenting on. If this option is turned on, I don’t leave a comment at all.
  2. Turn off the verification codes. Have you ever run your blog without it? Did you get much spam anyway? Is your traffic really that high? If you answered no to all 3, turn it off right away. I have had 3000 visitors to my Thermal blog in the last 2 weeks, and 3 spam comments - you really don’t need it unless you have a massive problem. People (including myself) hate word verification - it’s often very hard to decipher, and it has put me off leaving comments before, especially if I keep getting it wrong. Unless you’re getting several hundred spam a day you don’t need it - and if you are, may I suggest switching to Wordpress?

OK, those are my opinions, I’d love to hear yours. If you have any level of traffic to your site at all, I guarantee that the above 2 tips will increase the number of comments. Try it, make the changes and then make some posts asking for opinions on it, and/or other topics and see if your level of comments goes up. If you get a couple of spams, just delete them.