Sure! What kind of "venue" would you suggest? (Lord knows I have plenty of unfinished projects myself!)

A dedicated chan on IRC maybe?

EDIT: Also: I might take part if the "Finish it" weekend takes place, provided my wife takes care of the kids long enough.

If you wanted to make this big you could get a whole lot of hackerspaces to participate. I'd suggest IRC for now.

That's a very good idea. I'm up for that, remotely.