Chess Variants Pages
Comprehensive site with rules, information, histories, and links for a large number of chess variants.
chessvariants.com

Chess History Center
Service center for serious chess historians, clearinghouse of research requests and index to web resources.
chesshistory.com

Chess Dryad
Devoted to the history of California Chess, 12,667 chess games suitable for downloading into ChessBase, a large collection of articles and photographs, Shorman's thirty rules, and much more.
chessdryad.com

On the Origins of Chess
Collection of essays on the origins and history of this ancient game.
mynetcologne.de

ChessEbook - Chess History
Features games of World Chess Championships as well as biographies of World Champions.
chessebook.com

Culture et Curiosites de l'Echiquier
Historical and philosophical approaches of Chess with over 40 articles and original studies.
mjae.com