CafePress does many things right. They have a clean site, it's easy to use, and they have a compelling value proposition. I just ordered some personalized products for my people.
One idea I've only seen at CafePress is a "Pass It On" feature on their "Thank You" page after checkout.
Once you buy something online you're likely excited about your purchase. CafePress turns this emotion into profitable action by allowing you to send a $5 coupon to 5 of your friends. And, you must enter at least 2 email addresses...which gets you thinking about sending them to more. Sure you could send it to your own email addresses, and maybe they have controls for that. But even if this drives repeat purchase, and their margins are tall enough, why not?
