Turning Art into Cards

Sorry to have been away for a bit - real life has been very busy! I've received some nice things in the mail recently and when hunting around for a thank-you card in my stash, I came across a package of postcards I had made from some ATC's.  These got me thinking about the various services that will turn your art into cards or postcards.
I made these at www.moo.com several years ago, when I was considering the same thing. Moo offers a variety of sizes, and the quality was fine, especially given the relatively low price.  I think they took a long time to receive because of the company's location.
Recently, as part of a Japan fund raiser, I ordered some post cards featuring photography from Tammy Lee Bradley from Red Bubble. I was very impressed with the quality, cost and turn around time.  Then, I saw this article on the Digital Photography School blog about them. 
I'm thinking about putting some of my art up on their site. Before I do, I was wondering if any of you have experience with any other sites that turn your photography or artwork into cards. I'd love feedback or advice.