Here's a unique collaboration: the web comic "Axe Cop" is written by six-year-old Malachi Nicolla and illustrated by his 29-year-old brother, Ethan.
It has been going for a year now with weekly episodes. The stories are just as random as you might expect from a little kid but the drawings add touches that make it fun to read for adults as well. Naturally there's now an Axe Cop book and merchandise, appearances at comic conventions....
I don't think this project, which you can see at axecop.com, started with the marketability in mind--I'm pretty sure it was a fun way for a big and little brother to have an additional bond. But certainly it's something a smart marketer could run with.
When choosing a collaborator or a project of course the first question should be whether it will work on its own tersm--but it sure doesn't hurt if it has a promotable angle.
