Accessories. What a great business. I just bought a protective cover for my new iPod Nano. $34.95. You can see a couple samples here.
These things can't cost more than a few cents to produce.
I think it's true that the best new business ideas come from an entrepreneurial person noticing a problem and starting a business around the solution. Often, I fear that we're going to run out of problems and entrepreneurship is going to fade away.
But then I see a ultra-high margin business like this one built around a simple solution and, instead, my fears fade away.