Patterns Concepts
pdf: Patterns in Software Engineering
A Powerpoint tutorial on patterns in software engineering.
pdf: Software Patterns
An in-depth paper that discusses many important aspects of software patterns.
Software Patterns Overview
A extensive hotlist linking to tutorials, resources, conferences, applications and experts. Recommended.
Software Patterns Quality Criteria
Proposed Definitions for Evaluating Software Pattern Quality
Patterns FAQ Home Page
A discussion of design patterns with an emphasis on java development.
Patterns Approach to Building Software Systems
From the paper: "This position paper suggests an approach for building software systems using patterns, right from business architecture to software architecture."
Software Architecture and Patterns for Electronic Commerce Systems
From the paper: "The aim of this paper is to derive and identify patterns on an architectural level that are specific to the domain of electronic commerce systems.
Patterns: Powerful and Dangerous
Commentary.
Patterns and Software: Essential Concepts and Terminology
A comprehensive hotlist by Brad Appleton.
Patterns For Analysis and Design
Architecture & Design: Patterns
A comprehensive hotlist of patterns resources.
Design Patterns Resources
An extensive hotlist of design patterns resources. Recommended.
Requirements Patterns
Events and use cases are used as the basis for creating requirements patterns.
Notable Design Patterns for Domain-Specific Languages
A discussion of how DSLs and design patterns can be used to improve the efficacy of software development.
UI Patterns: History, Status, Applications
A brief tutorial on UI patterns.
Patterns in Model-Based Development
The roles of patterns in model-based design and the fundamental concepts underlying a generic notation for task patterns are discussed.
pdf: Pattern-Based Architectural Design Process Model
From the paper: "The goal of this work is to outline a pattern-based architectural design process model focused on quality requirements engineering."
Non-Software Examples of Software Design Patterns
"This paper presents a real world, non software instance of each design pattern from the book, Design Patterns - Elements of Reusable Object-Oriented Software. The paper also discusses the implications of non-software examples on the communicative power of a pattern language, and on design pattern training."
Video: Design Patterns
A lecture on design patterns. (56:13)
Video: Design Patterns in an Expressive Language
"In this session you'll find out the why, how, and when to apply patterns and the flexibility JavaScript offers that enables us to include these techniques in your code."
Patterns Catalogs
Data & Object factory
Excellent information of the G0F design patterns including UML models, code segments and more.
Hillside.net Catalog
One of the most widely referenced and used patterns catalogs. Highly recommended.
J2EE Patterns Catalog
"Each pattern in this catalog includes sample code from JavaTM BluePrints reference applications such as the Java Pet Store sample application." Introduction can be found at: http://java.sun.com/blueprints/patterns/.
ADF Business Components J2EE Design Pattern Catalog
Patterns that are used within the context of Oracle's Application Development Framework's business components building-blocks.
Patterns of Enterprise Application Architecture (P of EAA)
Martin Fowler presents a "brief overview of each of the patterns in P of EAA."
Welie.com Pattern Library
A fairly large pattern catalog that is applicable to both conventional and web-based applications.
EAM Pattern Catalog
The objective of the EAM Pattern Catalog is to complement existing Enterprise Architecture (EA) management frameworks, which provide a holistic and generic view on the problem of EA management, and to provide additional detail and guidance needed to systematically establish EA management in a step-wise fashion within an enterprise.
Info Design Patterns
A very slick patterns catalog with empohasis on content design. Recommended.
Books 
Over the past decade, many books on pattern-based design have been written for software engineers.
Design Patterns: Elements of Reusable OO Software
by Gamma and his colleagues is a seminal book on the subject.
More recent contributions on the subject include
Design Patterns
Design Patterns For Dummies
Head First Design Patterns
Design Patterns Explained: A New Perspective on Object-Oriented Design (2nd Edition) 
Implementation Patterns addresses patterns for coding and implementation issues that are encountered during the construction activity.
Other books focus on design patterns as they are supplied in specific application development and language environments. Contributions in this area include:
Pro CSS and HTML Design Patterns
SQL Design Patterns: Expert Guide to SQL Programming
Ajax Design Patterns
Design Patterns in Java(TM) (Software Patterns Series)
Applying Domain-Driven Design and Patterns: Examples in C# and .NET
PHP|Architect's Guide to PHP Design Patterns
Design Patterns in C# (Software Patterns Series)
Visual Basic .NET Design Patterns
J2EE Design Patterns
J2EE Design Patterns Applied
EJB Design Patterns: Advanced Patterns, Processes, and Idioms
Still other books address specific application domains. These include:
Software Architecture Design Patterns in Java
C++ Design Patterns and Derivatives Pricing (Mathematics, Finance and Risk)
Real-Time Design Patterns: Robust Scalable Architecture for Real-Time Systems (Addison-Wesley Object Technology Series)
Design Patterns in Communication Software
Classic books by the architect Christopher Alexander (Notes on the Synthesis of Form) and (A Pattern Language: Towns, Buildings, Construction)
are must reading for a software designer who intends to fully understand design patterns.
