Ben,
I'm the Director of Architecture at Hotels.com. We provide complete Web Services for air/car/hotel browsing and purchase via our Interactive Affiliates Network (http://www.ian.com). You not only have access to our entire travel inventory, but also earn a commission on each sale you make. I spoke on these services at last year's JavaOne and as far as I know, we are the only company that is providing this capability. Check it out, I think it is exactly what you are looking for, and more.
I'm willing to discuss further with you directly, but I'm not sure how to exchange personal contact information without putting it out there for the world to see. Maybe there is a way via Google Groups?
Brad
