I have a friend who is the business development manager for iStockphoto. You may have heard about them, when Getty Images bought them for $50million recently. They opened up the royalty free image world. You pay a small amount for an image, and then can use it as much as you like.
I've managed to get for readers of this blog and friends of emergent, a freebie from iStock. If you leave a comment with your e-mail address, I'll send you a log in, that gets you 25 free images and credits towards downloading some images.