From their site: Welcome to MOO. We're a printing company. Customers create a pack and then the pack is printed to pre-defined products. Create an XML document to determine where the user is placed in the process. For example, if you define a list of images that you want the user to select from to make a pack of cards, then they will be forwarded to the 'chooser' page. If you specify a list of images that you want them to actually use, and the 'crop' data associated with them then the user will be sent to the part of the process where they design the back of the cards.
Mashup contests can be a good way to reveal the variety of applications that are possible when the developer community is provided with a quality API. At the recent BarCamp London 5, Stefan Magdalinski, CTO of MOO.com, ran a weekend-long MOO API hack competition. The MOO service and API let users submit custom designs that can be printed onto products like business cards, sticker books, postcards, etc. These products can then be sold through an online store.
Along with the rapid growth of video APIs, the marketplace of photo-related APIs continues to expand rapidly. Since we looked at 36 Photo APIs earlier this year, we've added nearly a dozen new ones, and there are now 47 APIs tagged "photo" in our web service directory.