Mad discount tip: gives far more than 30% - it works with the 3 for 2 offer @ Lonely planet!
Lonely Planet currently have an offer of 3 for the price of 2 on their guide books. While this is fairly good, what's even better is that it works in conjunction with discount codes... namely the one below for 30% off. BUT this appears to give 25% off the total price of all 3 books, not just the two you are paying for....
For example, if you are adding 3 books at $10 each. You'd pay $20 (because of the 3 for 2 offer). BUT if you apply the 30% off code, it would take 30% off the $30, making this a further $9 discount, bringing the books down to $11.
Code = KAYAK30
Complicated - but discount-alicious!! Remember 9% buckscoop cashback on top of all that!!
** EDIT **
Updated with a 30% code thanks to ozpete :)