Just turned on this WordPress plugin and I like it. Find a post with comments, then look for the “View all posts by so-and-so” link.
Inspired by Jonathan Snook.
[UPDATE: Months later, this post is getting traffic from a Related Posts link right now, so I’ll point out that I turned this plugin off pretty quickly, but it was cool, and has some obvious applications. It might be a bright idea to use it on newspaper blogs running on WordPress as a basic way to give users a little touch of a profile without forcing them to register/login.]