Many of them are fairly recent start-ups with fairly small teams, which means there's a high likelyhood that the core team members on many of these kinds of projects are receiving shares in the company rather than actual money to begin with.
Thanks for the advice, Hodgman!
Yeah, I get the feeling that most of the successful collaboration projects were ones where the people involved already knew each other.
The groups that appear on forums with no experience at all, overly vague yet massive ideas, usually no talent, no idea of the legal/business side of things... that's a complete mess that I'd advise people to steer clear of.
As for successes, there's a studio in the same building as me, League of Geeks, who have built their game using a well defined profit-sharing system. The core of their team are actual development veterans coming from other studios, they've sat down ahead of time and worked out all the legals of doing a profit sharing system, and then they've planned out all the work involved and assigned 'points' to different tasks. IIRC, when they're finished, they'll add up all the points, and then everyone gets a slice of the profits depending on how many points they've earned.
They're only in early access now, but they're looking on track to actually finish their game. At that point, I think they're planning to release their "point system" for other devs to copy if they like.
Wow, that's quite an amazing game for an Indie studio