When I was in college I sold cars at a Ford Dealership. I noticed that salesmen who work on commission always out perform salesmen that work for a salary.
That lesson stayed with me.
How does that relate to designers? In a round about way. Please stay with me.
In my opinion, Fletch XXX is the best designer in the business. I approached him with an idea I had. I told him I'd pay him (XX) amount of money to begin creating alternate tours for my websites. In addition, he would receive (XX) percent of net sales that resulted from that tour. He would be responsible for creating all hosted galleries promoting that tour, banners, etc.
There are more details to it, but that's the basic overview. Fletch and I agreed on what the XX's above should be, and away we went.
Fletch chose to start with my Naked College Girls site. The first alternate tour he created is beautiful:
http://tour1.nakedcollegegirls.tv/
I love it! And Fletch has also created some beautiful hosted galleries to match it.
Fletch would have given his best whether or not he received a percentage of net sales from the tour, but I believe that since guys like him make guys like me a lot of money with their designs, he should be compensated beyond the usual set fee.
Thanks Fletch! You're the best!