"Branding" came up a few times when this was
initially being discussed.
QR code was never brought up. Might be a decent way to advertise and skirt potential legal issues. Though, then it looks more like commercial advertising and might have a great chance to be removed from books if it were seen.
The grand scheme was to have the curious search google and end up here, however a google search doesn't really lead to anywhere useful at this point and presumably we haven't dropped enough bookmarks to see any impact.
Might be a better idea just to point directly to amazon. Not sure though.