See
http://www.sahovski.com/products/acc/index.php
Sahovski is the publisher of the ECO series, Endgame books, and middlegame books.
The books may not be what you think. Normally, the books contain positions of games played during the last 6 months, or the past year (Grandmaster play).
A better source:
Chess Puzzles by GMs
Grandmaster middle and endgame play, listed by player.
You can have puzzles sent to your mailbox.
Another source: For beginners and Intermediates:
Chess Puzzles
Daily puzzles:
Daily Chess Puzzles
Also
Chess Puzzles
CHESS by L. Polgar is a training manual for beginners to Intermediates. The book has just been revised.
Middle Game books:
How to Play the Middle Game by Znosko Borovsky is still available. (Dover).
The Middle Game of Chess - A classic by Reuben Fine.
How Not to Play Chess - Znosko Borovsky also.
Recent books:
Attack With Tal has recently been released.