This was posted in the Deals section, thought it was worth bringing over here:
Originally Posted by jehane
Discount code: feb25au30
Offer valid from February 25, 2011 at 12:00 AM GMT through to February 27, 2011 at 11:59 PM GMT. This offer is not valid in conjunction with any other offer or promotion and cannot be used to adjust amount paid on previous purchases. Discount code is valid for 30% off any select eBook purchases excluding Hachette Book Group and all respective subsidiary imprints. Promotional code must be entered at time of purchase to qualify for this discount. Discounts cannot be applied nor the discount value refunded once a purchase is complete. We reserve the right to change or end this offer at any time without notice.
If you change the "au" to "ca", it works in Canada. I suspect changing it to "us" would work in the States, too.