David Sklansky's Theory of Poker
  by Jesse McLean
Sklansky's Theory of Poker is not an easy read, but it is one the fundamental books of modern poker

Andrew Kinsman's Poker on the Internet
  by Jesse McLean
One of many recent books written specifically about online poker, Andrew Kinsman's is a good beginner book.

Doyle Brunson's Super/System 2
  by Jesse McLean
Doyle Brunson (and friends) update the Poker Bible (Super/System I)

David Sklansky's Holdem for Advan
  by Jesse McLean
Holdem for Advanced players by David Sklansky is one of the most important books about the game.

Lee Jones' Winning Low Limit Holdem
  by Jesse McLean
Jesus doesn't want you to read this book!

DD Tournament Poker
  by Jesse McLean
DD Tournament Poker is a good way of practising for multitable tournaments.

Ed Miller's Small Stakes Holdem
  by Jesse McLean
This book is the graduate course in beating low limit games.