A Compendium of NP Optimization Problems: This is a preliminary version of the catalog of NP optimization problems.
Algorithms and Complexity: A collection of bookmarks by Heribert Vollmer.
Algorithms and Complexity: An overview of computational models and methods and how they relate to complexity, with links to selected papers.
Algorithms and Complexity Research Area: The Oxford University Computing Laboratory's area on algorithms and complexity, with links to lectures and information.
Average-Case Complexity Forum: Introduction and survey papers.
Challenging Benchmarks for SAT and CSP: Includes related links, references and a summary of the results for the SAT benchmarks used in SAT Competition 2004.
Complexity of Algorithms: A list of topics from a Computer Science course involving complexity of algorithms. HTML and PS format.
Complexity Theory: Two set of lecture notes by Prof. Oded Goldreich, Weizmann Institute.
Computability and Complexity: An online course on complexity.
Computational Complexity and Programming Languages: Summaries of talks of the DIMACS workshop (July 1996), collected by James Royer.
Computational Complexity Theory: Wikipedia article.
Computational Complexity Theory: Definition of the subject, links.
Constraint Satisfaction Problems: Research group in the Computing Laboratory, Oxford University.
ECCC - Electronic Colloquium on Computational Complexity: A forum for the rapid and widespread interchange of ideas, techniques, and research in computational complexity. Research reports, surveys and books; meetings, discussions and web resources.
Information-based Complexity: People, publications, prizes.
Lecture notes on Complexity: Collection of lecture notes by Prof. Eric Allender, Rutgers University.
P vs NP: Official version of the million dollar open problem in Theoretical Computer Science by the Clay Mathematical Institute.
Parameterized Complexity: Brief description, list of workers and problem compendium, compiled by Todd Wareham.
Probabilistically Checkable Proofs and Approximation: Pointers to some survey articles and their authors, by M. Bellare.
SAT Live!: A collection of up-to-date links about the satisfiability problem (solvers, benchmarks, articles). A discussion forum is available as well.
Stas Busygin's NP-Completeness Page: A proposal for solving NP-hard problems.