The divison would be based on awarded "shares" - so we're not talking stock exchange type shares (dont worry, I play the markets :) Im genned on realistic shares) but "share of the donation"
After I posted the original message I realised it was misworded. The project doesnt get X shares to divvy up. Rather share count is "infinite" and the project owner hands them out (either by automated means or manually) to others. So if 10 people contribute and each gets 1 share they recieve 1/10th of the donation pot (after costs etc.).
If the owner wants a "share" they must give themselves some ;)
Do you think company stocks started out that complex? No, they started out as an intuitive way to divide the profits of a business operated by multiple people, just like your intuitive way of dividing profits from a project built by multiple people.
Edge cases presented themselves, conflicts arose, opportunities for individuals to maximize profit came to light, and thus was our current system grown.
What happens when we decide, like businesses, that we need new classes of shares? Who gets paid first? Who has "voting rights"? What's the process to to pursue remedies if you feel you've been cheated, or that the "board" (project owner and his lackeys) has operated in bad faith to defraud share holders?
This is a complex issue even before you hit the psychological problems that others have already raised.
What I'm saying is that shares can't really divided in a trivial, algorithmic way. I like the idea in theory, but I think it's impossible to correctly implement.