One of the challenges on one of the episodes of Project Runway was for the designers to create fabric, and then make something from it. A couple of days ago, one of the craft bloggers I was looking at was designing her own fabric. The website she ordered it from is called Spoonflower.
They have several different types of fabrics they will print your designs on, including a quilting weight fabric, knits, and even upholstery. The prices are kind of high, compared to Jo-ann's, but you get to design your own pattern! Or, you can order someone else's design for your own use. The fabrics are mostly pretty wide, too. I can't wait to have some time to design some fabric!