I just received my Moo cards yesterday, and couldn't be more pleased.
I downloaded the card template from Moo, and doctored up my photos with GIMP. You can also just have Moo upload your photos from your Flickr, or from your Etsy shop, but you can't get quite as much control that way.
P.S. Sandy and I are working on a top secret project, and should have something to show for it late next week!