I’ve been doing a little playing around with the back-end of this blog.
Comments are now displayed with little profile pictures to go with them. You can choose your pic by selecting the “Edit Profile” option, when you’re logged in. And yes, that does mean that there are now commenter profile pages on here, into which you can enter as much, or as little, information as you want. ([Here’s mine](http://www.onemanandhisblog.com/profile/Adam/), by way of example)
If you’re not using any of the registration forms available on OM&HB, then the system will fall back on the [Gravatar](http://en.gravatar.com/) user pic service. If you register with them, your pic should automatically appear here.
I used the [User Profiles Pro](http://mt-hacks.com/20080227-user-profiles-16-support-for-mt-41.html) and [Gravatar](http://code.sixapart.com/trac/mtplugins/changeset/latest/trunk/Gravatar/?old_path=/&filename=Gravatar&format=zip) plugins to do this, along with [this set of instructions on displaying user pics in Movable Type](http://wiki.movabletype.org/Gravatar).