A few months back, I quietly added gravatar support to the site for commenters. I didn’t mention it, as I (apparently incorrectly) assumed almost everyone had a gravatar.
Since that’s turned out not to be the case, I’ve installed the excellent WP-monsterID plugin to generate avatars for those commenters that don’t have one. It’s really quite clever: it takes a hash of the commenter’s email address and uses some of it as a seed for a procedurally generated monster. There are millions of possible combinations, and as long as you keep using the same email address in your comments, you’ll always get the same monster. An even cooler side effect is that, you’ll take that monster with you to any other site that uses the same (sort-of-standard-ish) monster-generation code.
Of course, if you create yourself a gravatar, that will override your monster avatar, as well as appearing on all of the many sites around the net with gravatar support.
If you’ve commented here before, you can check back to the old posts, to see what your monster looks like. If you haven’t; feel free to comment on this post, for an example.