was just instore at wh smiths.
when you buy 2 selected hardbacks from a decent selection (majority of the top 100 charts) you get a free £10 gift card.
the cheapest combination i seen was £11 so in theory you could get 2 books for £1
you can combine the offer with the £5 off vouchers from http://marketing.whsmith.co.uk/images/51/WHSmith_Welcome_Voucher_18Oct10.pdf
so you could even get 2 books for free (taking into account the £10 back on the card)
i went for
ripleys believe it or not £12.99
justin bieber book £6.79
minus voucher £5
£14.79 to pay.
got back £10 on card..