Thanks for sharing, I used it!!
Not in the uk?The coupon is BOOKDEAL25 and expires December 14, 2014 at 11:59pm PST. You can use it on a book that is already discounted so you can get the Dungeon Master's Guide for $22.48.
More details:
http://www.amazon.com/gp/browse.html?node=10510039011&pldnSite=1