Perhaps you'll find what you are looking for at Fatpaint (
http://fatpaint.com) - Free online graphic design and photo editing application, specialised in giving you the tools and resources you need for creating designs and illustrations. Them you can view iPhone cases and iPad case with your picture printed on them. The case brand is Speck, and is of great quality.
It is possible to paint, draw make pages and see your pictures on products and buy them, such as: iPhone case, iPad cases, t-shirts, sneakers and much more. Checkout the tutorial videos, it is quite interesting ...
http://youtu.be/YkBnf5NGC8Y?hd=1
http://youtu.be/mnP495V9WHw?hd=1
http://youtu.be/GNctuQ5T858?hd=1
Fatpaint's facebook page:
http://www.facebook.com/fatpaint
What you guys think of it? I have spent 5 years developing this app. I would appreciate any feedback.
Thanks