i got a few promotional codes from apple in their newsletter emails. they were usually for 36euros (including vat) and could be used on items over a certain amount (in the email i have handy its for 366e (vat incl.))

the code was given in their newsletter and could be copy/pasted into that promo code box at ordering stage and discount is factored in immediately. the email i have here is all in finnish but the faq it links to is here (in english): http://email.euro.apple.com/store/evoucher/faq/fi/?cid=AOS-EDM-A30000076424