BOOKS FOR THE BOOK GOD!! A 40K thread

[The Artist Formerly Known as Hawk]

Some time ago a friend of mine got me into Warhammer 40k, via Dawn of War. Since then I've become more and more interested in the universe. Unfortunately there's only so many times you can read the wiki on everything, so I've decided to start reading some of the novels. From what I'd heard from various sources was that anything by Dan Abnet was pretty good, so I recently got myself copies of The Founding, The Saint and The Lost.

My sources were right. I've only just gotten through the first 200 pages or so of The Founding but the whole thing has been pretty fucking awesome so far, and I'm spending hour after hour reading through. However, there are quite a lot of other 40k books out there and I'm not sure what others are as great as these ones. Can anyone recommend any others to get once I've finished these 3?

Also I suppose you can use this thread for any other 40k novel discussion if you want.