I ordered some mini business cards from www.Moo.Com. I love them so much it might be hard to give them away!

Moo is an online printing service that will print your images (up to 100) on the back of each business card. You can edit each card so the image is cropped and positioned just right. Great fun and I am very happy with the weight of the cards and quality/speediness of the printing.  Artists trade ATCs but wouldn't trading Moos could be fun also?