For those interested in this sort of thing, I have enabled OpenID commenting on the site. The power of OpenID is that is a single sign-on system, so all you need is one OpenID that you can use to login anywhere that supports the standard. There are a multitude of organizations providing free OpenIDs, including some well-known names (LiveJournal, Flickr, Blogger, AOL, etc.).
I initially tried to add OpenID support by using the OpenID Comments for WordPress plugin, simply because it was the only WordPress OpenID plugin that I could find that also implemented an OpenID server (which allows you to authenticate to sites that accept OpenIDs). Installing it was very annoying, since it was more complex than a standard WordPress plugin installation (which consists of simply putting the plugin file or folder into wp-content/plugins), requiring confusing modifications to the code that controls the display of comments. After it was installed, I was disappointed to find that it did not seem to support the SREG extensions, which allow you to do cool things like attach your name or email address to your OpenID (so when you login with it, you do not have to re-enter your information again).
The entire exercise reminded me of why I do not like PHP, and by extension, WordPress (because many of the customizations are not clean and so make your code very difficult to maintain). I considered giving up and putting some time into writing a Django-based CMS to replace WordPress. After some serious thinking, I eventually decided to keep things as they are for the time being - writing a blog in Django is probably still a good idea, but I have no time.
As a result, I ended up just using phpMyID as the OpenID server (in retrospect, there was no good reason to integrate the OpenID server into WordPress to begin with) and the wp-openid plugin for commenting. To comment using your OpenID, just enter it in the field marked "URI or OpenID."