I know this is more of a lawyer question, however I figure someone here has probably done this and can give me a quick answer.
Lets take a moderately extreme case. I build an adapter for a website that translates the requests and markup into a more formal API. I then take this API I developed and build a mobile app on it.
So in short I take a site that doesn't support mobile. Build a mobile application, and then charge for the mobile application.
I am not talking about charging for any of the original product. Simply the extension to the product.
I ask because there is a site I would really like to build a mobile app for, because it would make my life easier, and it would be pretty gravy if I could earn some cash on the side from the work as well.