I've heard about gravatars a couple of months ago. But, I've only signed-up for one today.
And, since Expression Engine supports gravatars, I decided to enable the plugin here at ShaiCoggins.com. So now, if you've got a gravatar account and you leave a comment here, you'll have your own image ID. And, it should appear in all other gravatar-enabled blogs. In fact, I'm already planning to enable it at AboutWeblogs.com too.