A friend of mine was recently contacted to license an image he made to a company making 20,000 calendars and selling them for $12.99 each. They wanted his image for free. He wrote up a blog post about the experience which is a good read and raises an issue which is probably relevant (or will be soon) to anyone who has ever tried to negotiate this.
http://jeffreyswansonphotography.com...e-credit-alone