I read Penny Arcade religiously MWF, and today's news discribes a great mod. I emailed gabe and said I'd love to use his idea, and he, in turn, posts my email address. So if you want in on the action (testing, skinning, level building, or coding), start commenting.
We need skinning and level building the most, the coding shouldn't be too terribly hard.
I'll start up a sourceforge project, and get a mailing list going. When that's all done, we'll be ready to go.