plugin for recent changes display?

I'd like to have a "most recent changes" type of sidebar on my site ( http://www.obsidianportal.com ). The main idea would be to show recent activity on the site. I'd like to try and copy what they have on the left sidebar here: http://gaxonline.com

What I need is very simple, something along the lines of: - The user who did an action - A title/link to what they did - When it happened

It occurred to me that this is very close to some of the other plugins out there such as acts_as_rateable or acts_as_commentable in that it's a simple 3-way association between a user, a model, and something else (like a rating or comment).

Anyways, before I blab on too much, has anyone heard of a plugin that already does this? If so, great! I'll just drop it in. Otherwise, I'll get started and see what I can come up with.

Thanks, Micah