I don't know if this question is covered in this "other" zone, but here goes:
I am an ad agency and marketing company and have a client with a great product that will do well when taken to market. However, their funding has run out and I personally am hooking them up with an investor or two. For my considerable efforts, I want to write up a simple legal contract that will say that in return for the services I rendered and will render, that I (or my company) will take 5% of the net profits anything my clients makes on the sales of their product(s). Any advice on where to find template contracts for this?