Just found out that Book Depository is offering a 10% discount coupon.
Click on this link and enter
FCBZ10 in the coupon block when checking out.
It will only work if you follow the link, otherwise it doesn't give you the option to enter the coupon code. This is for the .co.uk site.
It says it's for Paypal and eBay users, but from my testing it works for everyone. With the free international shipping this should be of use to those of you who still enjoy physical books as well.
Valid until 20 January 2011