I picked up Tactics in the King's Indian at Half-Price books for five dollars. It is worth 5 times this price. It is 126 pages long, which may not sound like much but while reading you never feel that there is any lack of material. This book is organized around tactical themes, all stemming from the King's Indian defense. The book is lain out thus:

Introduction
1 Enticement
2 Deflection
3 Vacating or Seizing a square
4 Opening Files and Diagonals
5 Demolition
6 Exploiting unfortunate piece positions
7 Illustrative Games

The book is essentially a collection of games, all in the King's Indian opening, and all with some sort of tactical idea (though this sort of begs the question, why incorporate a section called Illustrative Games?).

Why buy this book?

-It is cheap (Used is $10 on Amazon)
-Studying tactics in an opening is a great way to learn to play it
-It has plenty of instructive, beautiful but relatively unknown games
-It deals with lesser known tactical themes (though there are many forks in here too)
-The book deals with obscure but wonderfully creative moves and ideas

I suppose my only complaint is that some of the commentary on variations of the King's Indian are a little outdated.