One site that allows the above is Tailcast which encourages amateur and professional creatives to join the personalised print-on-demand product market through submission and commission based sales (20% commission on all sales that feature their designs).
The result is unique and original content available for consumers and an outlet and opportunity for creative people with great ideas to make money.
Its pretty cheap and theres a whole host of various things to print on.
I can't front on you guys, the above image and feel of the website may seem a tad bit dated. But the actual idea is pretty good and can help those of you trying to build up a diverse portfolio of various different physical mediums of your photos or illustrations /designs.
For further info on Tailcast just (click)
Loving bntl like a fat kid loves cake.