As someone who has worked as a consultant and hired them, it's hard to imagine a piece of work that I'd be willing to pay an outside contractor a continuing percentage for. Products,definitely, but that assumes a more or less tu rn key solution that I am not responsible for maintaining. But code rots, marketing is forgotten, and business practices must continually adapt in the face of changing realities on the ground, as it were. If I'm paying you for your expertise, I'll leave the money on the nightstand , but you're not getting half my stuff. ;)