Found a website just now through twitter, worth having a look if you have a book out or planning on getting one out. It basically buying constant advertisement for £50 a year, giving you a higher reach than usual. I havent really looked into it to be honest just seemed interesting. I know for sure that when you publish on amazon they are doing their own promotion these days and it has resulted in more sales of the books, provided you have a book worth reading to be honest. But for £50 a year why not, it can only help.