Head First Design Patterns

Covered in detail       Brief Introduction

Strategy (p24)
Observer (p44)
Decorator (p88)
Factory Method (p131)
Abstact Factory (p153)
Singleton (p171)
Command (p201)
Adapter (p241)
Facade (p264)
Template Method (p286)
Iterator (p325)
Composite (p356)
State (p410)
Proxy (p460)

Builder (p614)
Prototype (p626)
Bridge (p612)
Flyweight (p618)
Chain of Reponsibility (p616)
Interpreter (p620)
Mediator (p622)
Memento (p624)
Visitor (p628)

Design Principles

Amazon reviews

Insufferably cute, but a very good intro nonetheless, April 2, 2006
Fun way to learn about design patterns, June 7, 2007
Easier to read than the original, May 20, 2007
Cheesy design but excellent content, March 13, 2007
Solid concepts with liberal amounts of sugar to help it go down, February 28, 2007