I've just discovered CardCub, where designers, artists and illustrators can upload their designs for greetings cards to sell and get paid royalties when people buy them.
Sounds like a brilliant platform for all sorts of creative people :)
I've just submitted a couple of ideas for christmas cards. It takes a week or so for designs to go up, and there's some brilliant work on there already, so I'm going to see what else I can come up with!
After all, I have a ridiculous amount of time on my hands seeing as no one seems to want to employ me :(
What's really great is that you get to design all aspects of the card - front, back and inside, and you can do them landscape or portrait.