a coworker has recently brought me on board for his startup. It's an excellent idea and I think it may end up being *very* profitable. so far there are four of us. i'm the information architect so i'm responsible for the UI and usability of the application (web application). we all work together to vet the basics of the application and what it's features and requirements are etc. we're working on patents, business plan etc so we can go for private funding.

Long story short, we're just about to start discussing the details of stocks and ownership etc. How in the world do I determine what my ownership in the company should be? The basic idea behind the company is my coworkers concept, but i (and others) have all contributed considerably to it's development. I have no reason to think i'm going to be taken advantage of, but i want to be prepared to discuss it intelligently. Any suggestions? Any good references that you can recommend?