If it has been written by Dan Abnett, it's worth reading (or watching, in the case of the Ultramarines movie being made right now).  So Ravenor is totally worth it, as well as Brothers of the Snake (even if only for the battles at Ganahedarak where the Iron Snakes go all Ancient Spartan on a green tide of Orks with a shield-and-spear phalanx) and every single Gaunt's Ghosts novel, which fortunately should be in three omnibuses by now plus the newest novel of Blood Pact.  Titanicus is awesome too since it has lots of Titan-on-Titan warfare in it.

Of course they precede the other novels... They come before everything else in Warhammer 40,000.
They occur in the 31st Millennium, rather than the 41st.

The Horus Heresy novels are pretty good, especially since Abnett wrote a couple of them, Horus Rising (the first HH novel) and Legion, which is about those cunning bastards in the Alpha Legion.

You really should grab the Gaunt's Ghosts novels though, especially if you're a fan of the Imperial Guard since there aren't any Astartes involved in on-screen combat actions, so everything gets done by the Guard, one bloody meter at time, or in the case of the Tanith-First-and-Only, sneaking up behind the enemy with their camo cloaks then stabbing them to death with their Scottish dirks.  Compared to the rest of the 40k fluff, the Gaunt's Ghosts novels really give a sense of the Guard being competent soldiers rather than a bunch of red shirts who die so the tanks can live.

Yes, Brothers of the Snake (which takes place sometime in the 41st Millennium), and in the Horus Heresy series Horus Rising and Legion.

Have to get that one next.  I ordered the Gaunts Ghosts Omni,  Heresy:  Horus RisingSpace Wolf Omni,  Ravenor Omni,  Blood Ravens Omni,  Heresy: Legion,  and False Gods:  Heresy Takes Root.  Again appreciate all the feedback.  I still feel like I'm only scratching the surface though.

I'm gonna take my chances.  I kinda want to know why they allude to the chapter not having much of a recorded history unlike the other chapters.  Plus the Blood Ravens are the chapter that got me into the whole Warhammer 40k thing.  Call it misplaced loyalty.  I did notice that it got lukewarm reviews at best on amazon though so you're not alone in feeling that way.

Also a couple easter eggs in appreciation of the feedback.  The first is a trailer for the movie that's supposedly getting made and the second is just a badass music video featuring cinematics from the games.

http://www.youtube.com/watch?v=aFHKIFDjk9I

http://www.youtube.com/watch?v=Sl3_ZOeL2Z4

I wouldn't worry too much....certainly not a necro-thread....it's still the same year at least...

Read the Ciaphas Cain books.  Each one is addictive.  If you like Black Adder, you'll love this series

I hate to be the bearer of bad news, but the Blood Ravens are more recently added chapter, and weren't around during the heresy. Their gene seed is a combination of Blood Angels, and the Srorm Crows chapters. The Storm Crows no longer exist, because of an incident like the book Flight of the Eisentein, and some fell to warp creatures, while most just joined them. They have since been expunged from Imperial records.

Black Adder is an older British comedy program, look it up, you may find some episodes online, but it has nothing to do with anything Warhammer.

I'd be careful and not buy entire series or compilations to begin with.

The Gaunt's Ghosts, for instance, I found incredibly boring and repetitive and just stopped reading about 2/3 through the first book.
They are either being killed off in a battle or being transported to the next battle. Repeat ad infinitum. That's the entire "story".
That I don't finish a book happens an estimated 1/300 books so this is a rare exception.

The only W40k books that I found to have a story were the Ciaphas Cain series. Definitely not your stereotype heroic space marine(tm) in blood-spattered armor.
But again - the characters don't really develop at all and start getting a little repetitive after the first 3 books or so.
Still way above average for W40k books where in most even the story doesn't develop at all.

Thanks for the clarification I have to admit my only references were the Blood Ravens Omnibus and the RTS games.

@Jarmox, I'll have to check those out.  I've gotten pretty aquainted with Abnett's 40k work (ie Eisenhorn, his contributions to the heresy series, Gaunts Ghosts, and partially through Ravenor.)  But I hadn't heard too much feedback on the Ciaphas series.

I'd recommend "The Last Chancers" if you're interested in seeing the universe through a humans point of view.  In fact I have a video review on that series at choppyreviews.com, or you could find my blip channel.  I'm new at this so I'm open to suggestions on my reviews.