The Horus Heresy Collected Visions: Iconic Images of the Imperium, Betrayal and War
Found this buried in the latest Play.com promotion.
While not for everyone, this book is stunning! I was in Waterstones just the other day trying to justify spending £30 on this and Play.com go and put it up for sale at half-price.
You can download a few pages in pdf format from here http://www.blacklibrary.com/product.asp?prod=60040181012&type=Book
this will give you an idea of this books quality.