Growing article, with links to many related topics. Wikipedia.

Patterns developed by Martin Fowler, a specialist in object-oriented software, building business objects, the UML, patterns, author of "Analysis Patterns" and "UML Distilled" books. Also features a collection of links to related subject areas.

An examination of this most frequently deployed of software architectures. A casually, even haphazardly, structured system, the organization of which is dictated more by expediency than design.

Fine resource on many aspects of patterns, anti-patterns, and pattern languages.

Very useful pattern information. Includes articles as well as discussions in the form of the WikiWikiWeb.

Resources related to pattern languages for interaction design, including user interface design.

Design patterns for many uses: graphic user interfaces, Web, mobile interface; background information, links to literature and other collections.

Contains patterns, links and literature on object/relational database access layers.

A pattern language for designing user interfaces and other artifacts.

Reuse techniques in HCI - Pattern languages For Usability (MVC, Safety, Internationalisation). Also, software development and learning about patterns.