Good Books on the half open defences to 1.e4

The Pirc in Black and White by James Vigus is a given whether you're white or black in the Pirc. Not a reperertoire book for one side, but covering most stuff - even interesting sidelines and move order issues. It will be a useful reference for at least a decade!

On the Caro-Kann, Houska's and Well's books have happy readers - at least that's what I've heard. Houska's book is a rep for black and probably a good place to start for those who want to take it up as black. While Wells should cater for both colours

I really liked Melts' book on the Qd6 Scandinavian when it was new. Don't know if it's dated nowadays, probably slightly at least in the sharpest lines with Qd6 + a6, but if you're looking for a low maintainance defence to 1.e4 - this is one of the best options (i.e. Qd6 + c6). Emms book on the the whole Scandinavian complex is probably the best reference book available - though it would've been more overviewable without the traditional illustrative game acting as a spine for the comments - tree format rules!

Starting Out Alekhine's defence by John Cox, is another given if you're interested in it as black. Far more detailed than 90% of the other "starting out" books, and with text comments that contains more than usual standard phrases.

Personally, I'm finding 1.e4/d4 Nc6 more and more appealing - though that seems to be happening every tenth year or so... Anyway, there's a shortage of good books on it, especially good books still in print. Berdichevsky's book is a collection of informator style commented games, giving a good foundation for the main lines of 1...Nc6 vs e4 and d4. The lack of text comments may scare off most readers - but personally I like the bare facts without all the standard phrases. (For example, why is white/black always "winning easily" even if the game takes 40 more moves, and in the end the defender escapes with a draw?)

Play 1...Nc6 by Wisniewski is one recent addition to the black side, offering a repertoire against most white moves. Though I'm more interested in Nc6+e5 than the Nc6+d5 which he recommends, and some of his choices I frankly don't like, e.g: 1.e4 Nc6 2.Nf3 Nf6 3.e5 Ng4 which I tried and abandoned some 15 years ago...

A Complete defence for Black by Keene and Jacobs (in 1996) is an old book which also goes for a repertoire for black. They could have spent more energy on analysis and comments, but if you find it cheap somewhere (check the two links I give at the bottom of the Good KG books page) it's not without merit.

For those who can manage the german language reasonably, I'd still recommend 1...Sc6 aus allen Lagen by Keilhack and Schlenker from back in 1995. At times they may be too optimistic, but on the other hand they give plenty of food for thought too, as it's two insiders who guide you! And it's not a repertoire book! :)
21/9-09 - just noticed that there might be an updated version of this book in the making, by "Ilja Scheider and Friends", see www.kaniaverlag.de for more details...

21/9-2009. Michael Melts has published a 2nd edition of his Scandinavian defense - The Dynamic 3...Qd6 (yes, the 1st edition is also linked above). By the way, the cover picture is the same as on the first with an additional text "2nd edition,Revised and Enlarged" but on amazon they only show the first page of the book instead - maybe to avoid confusion?
Anyway, I really like it even better than the first - it's not often that a "revised edition" is actually a revised edition, but this one certainly is! And a lot has happened since the last edition - even the top GMs seem to have caught on (recently even Kramnik tried it in speed chess vs Judit Polgar) probaby because Tiviakov took it up some years ago. So there's a wealth of new info to process in the book.
As with edition 1, the only downside is that the author is more interested in pure chess moves than explaining ideas and manoeuvres. There is a new chapter added for club players, with a suggested repertoire for black, which is nice - but adding a few pages of uncommented game scores with a diagram in each, with the only text comment being: "Let's take a look at some games with this pawn structure:" is the really lazy way out, and not worthy of the rest of the book.
But if your rating is over 2100 and you're *really interested* in this opening, then it's a must buy! - If you're not so motivated or want the material pre-chewed for you, you might want to check out the 2nd edition of Andrew Martin's "The Scandinavian the Easy Way" instead, - though it's not on amazon yet as far as I know.