These are in no special order but look at the 'or Buy New' price to see how great these sales are. Most are 60% off or lower. These are printed books paperback and a few hardcovers but double check the Kindle prices as some are also on sale in that format too.
A quick note about bargain books though... sometimes (but not always) they will arrive with a black permanent marker swipe along the top or bottom edge of the pages. They don't bother me really since I'm getting a brand new book in perfect shape save for the mark which is only visible when looking at the edge. I find them less from Amazon but always on books I buy on 'clearance' locally.