Cant see this being posted anywhere so here we go...
AMAZON are offering students a further 5% off Amazon.co.uk's thousands of low prices on books, music and DVDs. All you need to do to take up the offer is own a valid NUS Extra card, and follow the instructions below on how to get your extra 5%.
 Take a note of the promotional code as displayed on the NUSextra website.
 On the Amazon.co.uk website, select the items you wish to order using your shopping basket (please note you cannot use the 1-click shopping method when redeeming a promotional code). In the order form you'll see a box that says "Have a gift certificate or promotional claim code?" Enter your promotional code into the box and click the "Apply" button. You will be able to see that the value of your promotional code has been deducted from the total cost of products in the order summary.