Here's an idea that I don't have time to work on, but perhaps you do: plastic covers for the Kindle that have the cover of a book you are reading printed on them.
I love the Kindle, but I lose the whole display behavior of people seeing what I'm reading. So here's a way to solve that: Kindle Kovers. Imagine a slim plastic jacket for the Kindle. On one side there's a space for the screen and keyboard, on the other there's a laser printed image of a book cover that everyone can see while I'm reading.
Such as service should be quite doable. Kindle users could forward their Kindle receipts to Kindle Kovers and then get sent a cover in return with the appropriate image on it. Since the Kindle receipt contains the book name and the buyer's name and address the service would be simple to use.
To get the images it's just a matter of parsing the book name and grabbing and printing the large size image from Amazon.com itself. All you'd need are a supply of plastic jackets of the right Kindle size and a color printer.
To make money you use Amazon.com affiliate links. When people send a request through you send them a link to confirm the dispatch of the cover (correct address, Kindle size, etc.). One that page you show related books (since you know the book they are buying) with affiliate links.
If you implement this idea, slip me 10% :-)