Any of the old RARE developers if it was for a sequel to Conker's Bad Fur Day.
I'd also definitely help kickstart a Team Meat or a Twisted Pixel project.
As for big name developers, Mikami and Kamiya in Platinum Games are two developers I'd definitely get behind. Also Inafune if he was making a new Mega Man or Mega Man X game, but only if it was a 2D platformer.
EDIT: And now that I think about it, I'd pour tons of money if the team of Nomura, Sakaguchi, and Uematsu got together to make a new Final Fantasy in an old-school style.