I'd love to get you to sign a book. Well, how do you sign an ebook?
One idea (that I'm shameless stealing from... I believe Terri Osborne) is to simply make a binder of printed cover images.
Actually, I did that first. Terri then nicked the idea and ran with it.
Cover on one side of a white unlined index card, marketing copy and/or contact details on the back.