Fine Art America (the company through which I offer prints, greeting cards etc. on demand on my artist website) has recently added phone cases to their product portfolio. Right now, they are available for the iPhone 4/4S, iPhone 5/5C/5S and for the Galaxy S4. That’s a pretty nice way to have a very individual case for your phone, and support your favorite photography artist at the same time. ;-)
Due to the nature of the phone cases, images in portrait orientation will obviously work best, but the resolution of any of my images is sufficient enough that a vertical strip cropped out of a photo in landscape orientation will work too (if you must;-).
Check them out on my artist website, click through to the 1:1 view of any photo, and find the phone case option at the bottom of the product selection on the right. Here’s an example: iPhone 5 cover of Tall Maples.