People are able to learn fastest in different ways; some people prefer the structure of reading books, others like discussing hands as you're forced to think analytically and interact and, of course, we all enjoy watching pros crushing the games in training vids.
For a long time most poker books were extremely basic and any information you gleaned from reading them could be quickly surpassed by spending a couple of weeks/months trawling the 2+2 stickies and signing up for a training site. There were also very few books on cash game material and almost nothing for 6max. Over the last couple of years there have been a number of expensive ebooks released and, recently, authors have been releasing "affordable ebooks" for micro/small stakes players.
What was once only valuable for beginners has now become a viable training tool for almost all levels of player. The purpose of this thread is to give you a list of useful cash game books and to facilitate discussion and review. The better reviews will be linked in this post underneath the books, I'm sure Matt and Vitas will help me out with this

.
Strategy books
Theory of Poker - David Sklansky - ~$20 - Available
here and
here.
The classic book on poker theory.
No Limit Hold'em: Theory and Practice - David Sklansky and Ed Miller - ~$20 - Available
here and
here.
Theory of Poker for no limit hold'em.
Poker Blueprint - Aaron Davis and Tri "Slowhabit" Nguyen - $37 - Available
here.
DailyVariance Publishing's micro stakes offering.
Ryan Fee's 6max guide - Ryan Fee - Free - Available
here.
More of a guide then a book but some very useful content and you can't argue with the price.
Super System 2 - Doyle Brunson - Free - Available
here.
Another classic, available for free on Doyle's site.
Winning Strategy in No-Limit Hold 'Em 3 DVD Set - Rob "BobboFitos" Eckstut - $59.95 - Available
here.
Based on content from Rob's $750 ebook.
Short-Handed No-Limit Hold'em - Jay "Krantz" Rosenkrantz - $48.54 - Available
here.
2 DVD set.
Harrington on Cash Games Vol 1 and 2 - Dan Harrington and Bill Robertie - ~$48 - Available
here and
here.
Although written for full ring games, some of the concepts should still be applicable.
Harrington on Online Cash Games: 6-Max No-Limit Hold'em - Dan Harrington and Bill Robertie - ~$32 - Available
here.
To be released in June 2010.
Mathematics of Poker - Bill Chen and Jerrod Ankenman - ~$20 - Available
here and
here.
Game theory applications for poker.
Secrets of Short Handed No Limit Hold'em - Danny "theBruiser500" Ashman - ~$20 - Available
here.
A former online high stakes pro's take on the game.
How to Beat No-Limit Hold ‘Em 6-max Cash Games - Bill "bigbabyjesus" Vosti - $50 - Available
here.
Includes free videos.
Professional No Limit Hold'em - Ed Miller, Matt Flynn, Sunny Mehta - ~$20 - Available
here and
here.
Focused on planning hands and commitment.
Small Stakes No Limit Hold'em - Ed Miller, Matt Flynn, Sunny Mehta - $100 - Available
here.
The sequel to Professional No Limit Hold'em, this book is aimed at players looking to beat online $200nl games.
The No Limit Hold'em Workbook: Exploiting Regulars - Tri "Slowhabit" Nyugen and kingsofcards - $117 - Available
here.
The sequel to Let There Be Range.
The Poker Puzzle - Oliver "Improva" Marx - €400 - Available
here.
Includes videos and 2 hours of coaching.
Easy Game - Andrew "BalugaWhale" Siedman - $949 - Available
here.
Available in two volumes.
Let There Be Range - Tri "Slowhabit" Nyugen and Cole "CTS" South - $947 - Available
here.
The first book from DailyVariance publishing, also available in two volumes.
Bobbo's Bible - Rob "BobboFitos" Eckstut - $750 - Available by contacting
BobboFitos.
The original expensive ebook.
Discussion Thread.
Memoirs of Aejones - Aaron "aejones" Jones - $5000 -
Website. Available by contacting
aejones.
Audiobook with 10 chapters, 6 discussions and 1 update.
Discussion thread.
Psychology books
The Poker Mindset: Essential Attitudes for Poker Success - Matthew Hilger and Ian Taylor - ~18$ - Available
here.
Elements of Poker - Tommy Angelo - ~$30 - Available
here and
here.
For a beginning player I'd recommend picking up theory of poker, although a little dry it covers a lot of important, fundamental concepts. For a micro stakes player I'd recommend getting Poker Blueprint, although I haven't read it I've heard good things about it. Be sure to pick up BobboFitos' 3 DVD set. After that I'd recommend getting Small Stakes No Limit Hold'em, although it's a little more expensive, it's well written and covers a lot of important material. Of the more expensive ebooks I only have Bobbo's Bible and Memoirs of Aejones and can recommend both to players looking to move up to mid/high stakes. For people who are interested in game theory or the more advanced mathematics in the game, Mathematics of Poker is highly recommended.