Looking for a notify plugin for 2.0

I’m using 2.0 and I am seeking a plugin that enables users to be notified when a comment is made to a particular post.So far none of the mail plugins I have seen do this on a per post basis.

If anyone knows of a such a plugin can you plaese point me in it’s direction?

Here is an example I saw on ifelse’s site: https://img21.imageshack.us/img21/6480/notify2ct.gif

Thanks ??