Competition is stiff, but if you are a savvy designer, this is a good way to pick up extra dollars. Even better, if you are an artist. this is a good way to make your art skills pay off. Consider that every design will need to have a reason why the customer should buy the book or follow that person on Twitter to have a real impact. Twitter backgrounds, in particular, are in hot demand right now. For measurements and caveats of Twitter backgrounds, read How to create your own Twitter background.
