The Inner Game of Chess - How to Calculate and Win by Soltis is very good.  Improve Your Chess NOW! uses an interesting training method with blindfold analysis and stepping stone diagrams to improve your visualization of the board and variations and improve the depth of your calculations.  Everyone seems to love this book and I think you should definitely read it.

For puzzle books Imagination in Chess has some interesting material but I'm not sure if it's worth the price for a puzzle book with some short material on calculation methods.  The It's Your Move books by Ward are excellent and fun to read.  These aren't the same old problems.  You are given a position then a list of thoughts from imaginary players offering hints on a plan and you have to pick the right way to proceed based on this.  It's a 'find the best plan' book.  I think you would also get a lot out of Positional Sacrifices by Neil McDonald.

I prefer to do tactical problems on the computer.  The 'Play as' series which are included in the Convekta World Champions software is very good.  Play as Tal by Convekta is a fun one.  Of course CT-Art is recommended by everyone.

My absolute first choice is the Encyclopedia of Middle Game Combinations published by Informator.

My second choice may be a bit surprising.  It's The Ultimate Chess Puzzle Book by John Emms because it has so many wonderful positions from Soviet championships.

An interesting online source is chessgames.com, which offers one puzzle a day.  The Wednesday-Sunday puzzles are progressively more difficult, and I have seen at least one FM mess up some analysis there.  

BTW, Tal used to watch a TV show for beginning chess players, and he said the tactics that were shown to beginners often inspired him.  So perhaps a first book of chess tactics may be useful!

Hi AB,

Based on what I've seen, I would have thought that you'd find what your looking for in the following books:

Secrets of Chess Tactics by Dvoretsky
Test Your Chess IQ: Grandmaster Challenge by Livshitz 
or maybe, Test Your Chess IQ: Master Challenge