Gravatar Latest Commenters plugin?

I’m looking for a gravatar [or more if available… ie OpenAvatar] plugin that will allow me to have the last x number of commenters gravatars show up in a list, 3 wide by x high in my sidebar. I’ve looked around and I know they exist, but I cannot find out what plugin these people are using… Since I can’t remember any of the sites i’ve seen it at, i’ve included a PS of what it would look like on my shop. Anyone who can point me in the right direction would be hawesome!

I’m using wp 2.6 and already have other gravatar functions built into the theme [author, commenter, latest comment, etc]. This is the last thing i’m looking for.

https://heroesarg.com/main/images/latestcommenters.jpg for the picture.

Thanks!!