I have a simple HTML landing page setup for an online product I want to sell. This product is a hardcover book. I want to be able to allow other people to setup their own landing pages and make a percentage of the sale from their site. What are some good payment processors or payment gateways that make setting up an affiliate system easy and fast?

Clarification - When someone purchases an item, I want (whatever the payment processor is) to automatically route a percentage of that payment to the affiliate and the rest to the original author.) Are there any payment frameworks that already do this?

I've found a few sites that let you do this, but they seem to restrict you to digital purchases only. However, my sites is selling a ship-able product and the affiliate system needs to support this.