Supermarkets tailing vouchers to your spending isn't new, but I've noticed recently online shops doing the same. I bought a camera through Amazon and suddenly had a front page full of cameras with discounts on them. My friend checked the same cameras and wasn't offered the discount. The thing is that since I'd already bought a camera I wasn't going to buy another one! I did joke that it was so Amazon could look generous without actually losing any money... Do you ever buy through these personalised deals? What do you think the benefits are to the merchant?