1. Pawn Structure Chess - GM Andy Soltis
This and #2 were responsible for me going from USCF 1800 to 2000, and it made so much sense of what the opening was all about. If you're having trouble finding middle game plans, studying how to play the various pawn structures will improve your game.
2. The Art of Defense in Chess - GM Andy Soltis
"Most games are not won, they are lost!" - Soltis. Whether one side crashes through often depends on one key tempo, and knowing when and how to throw a spanner into your opponents plans can make all the difference between winning or losing. IMHO the first step in becoming a winning player is becoming much harder to beat, and all great players are noted for how well they defend, too. (e.g. Karpov, Fischer, Carlsen, etc.). If you change your mindset that there are only two results in chess (winning and not losing), you will increase your rating.
3. The Art of Attack in Chess - GM Vukovic
A concise encyclopedia of the main elements of attacking play with classic game examples.
4. The Games of Robert J. Fischer - Wade & O'Connell
No Fischer Fan's library is complete without this book. This is THE Fischer book - 700+ games, many fully annotated.
5. 500 Master Games of Chess - Du Mont
Pull up a chessboard and sample this buffet of the great masters, all organized by opening. The weath of annotations makes this a great source of opening ideas for you games.
6. The Sorcerer's Apprentice - GM David Bronstein
Ounce for ounce, Bronstein was one of the most imaginative and creative players ever. Narrowly missing winning the World Championship from Botvinnik, he pretty much single-handedly resurrected the King's Indian Defense into a powerful weapon. If you love deep combinations conjured from thin air, this is a treat!
7. My Best Games of Chess, 1908 - 1937 - GM Alexander Alekhine
An unparalleled master of combination play, Alekhine's genius coupled deep strategy with eagle-eyed tactics. See his games from the San Remo tournament for an example of his dominance.
8. Zurich International Chess Tournament, 1953 - GM David Bronstein
A treasure-trove of first-hand accounts and annotations by Bronstein elevated this to classic status among serious chessplayers. Many liken it to a textbook on how to play the middlegame.
9. 100 Select Games - GM Mikhail Botvinnik
Few modern GMs write down their thoughts and chess understanding like Botvinnik did. Here, you get 100 lessons in modern positional play and some sense of the depth of analysis required to be a top master.
10. Morphy's Games of Chess - P. Seargant
Few modern GMs are as deadly in their understanding of the inititative and it's coupling to quick development as was Paul Morphy. If you love to see pieces and pawns sacrificed with laser-like logic, these games will be immensely entertaining and instructive.