To be honest, the affiliate program through cafepress has been a great money maker for me. It's simple and easy to do. How it works is you go to cafepress.com and sign up for the affiliate program. You can then find other cafepress stores who are also involved in the affiliate program and link to their site from your own with your own special affiliate ID number. Every time someone uses your link to purchase something from this affiliate store you receive a percentage of the sale! You can also network with other cafe press stores and have them link back to your site with their affiliate number.
I have read a lot of merchants complain that affiliates take part of their profit, which is true, however I look at it as being extra sales that I probably wouldn't have made if it hadn't been for these other sites linking back to my page! If it's bringing more people to my site then that is the most important thing!
If you're not sure where to start to find other stores who are also in the affiliate program you can go to the message boards and look for threads regarding affiliate programs or you can post that you are looking for affiliates and welcome people to link back to your store. It's a great way to get your name out there to more people and to maybe earn you a few extra sales or a few extra bucks! It's great either way because you are always earning money!
You can make a page like mine to let people know about the affiliate program. People don't have to own a cafepress store, they can easily just sign up for the affiliate program and get their ID number and just link back to your site from their own, whether it be a personal website, a myspace page, a blog or a business page.
You can find a lot of very helpful information on the affiliate program through the community message boards at cafepress!