Blogger has recently added support for posting comments by authenticating with OpenID. The integration is now live for all Blogger blogs and that means you no longer have to show your identity by using a Google account. You already have an OpenID if you have an account at AOL, WordPress, LiveJournal or at one of the other OpenID providers. You can be your own OpenID provider, but this is a little more complicated.
A simple way to use your own domain as an OpenID is to delegate it to another OpenID provider. That means you should get an OpenID from a site like MyOpenID and add these two lines in the head section of your homepage (you should replace http://NAME.myopenid.com with the real OpenID):
<link rel="openid.server" href="http://www.myopenid.com/server" />
<link rel="openid.delegate" href="http://NAME.myopenid.com/" />
Now you can use your domain or subdomain everywhere you're allowed to enter an OpenID. To post a Blogger comment, select "Any OpenID" from the drop-down and enter your URL. You'll be redirected to the OpenID provider to enter your password.
Google removed the option to enter your URL when you don't sign up with a Google account, but you can still show the URL if you use OpenID.
Update: Blogger brought back the option to enter a URL when post unauthenticated comments.