AuthorGraph has been around since spring 2011 (originally called kindlegraph), and is slowly catching on. The site offers a way for authors to send their autograph with one of their titles, and even a personal message if they wish. Readers who already have books can request autographs from their favorite authors.
Information on how it works is straightforward. It is necessary, however, to have a Twitter account (readers and authors). It isn't necessary for the author or the requester to have a particular brand of eReader. A nice keepsake from authors to readers; a nice incentive when readers are making book choices.
