Rules

• The F.I.D.E. Laws of Chess: http://www.chessvariants.com/fidelaws.html
• Fischer Random: http://en.wikipedia.org/wiki/Fischer_Random_Chess

Protocols

• Detailed UCI specifications: http://download.shredderchess.com/div/uci.zip
• Example of UCI usage: http://wbec-ridderkerk.nl/html/UCIProtocol.html
• CECP/XBoard specifications: http://home.hccnet.nl/h.g.muller/engine-intf.html
• FICS: http://freechess.org/Help/AllFiles.html
• FICS bot howto (simple): http://blog.mekk.waw.pl/archives/7-How-to-write-a-FICS-bot-part-I.html
• ICS: TODO
• dgtnix: Does it exist? Home page is here: http://dgtnix.sourceforge.net/
• chess over XMPP proposal: http://www.xmpp.org/extensions/inbox/chess.html

Formats

• XMLChess (mostly ChessGML): http://www.xml.com/pub/a/2004/08/25/tourist.html
• ChessGML specifications: http://www.saremba.de/chessgml/why.htm
• PGN specifications: http://www.very-best.de/pgn-spec.htm
• FEN specifications: http://www.very-best.de/pgn-spec.htm#16.1
• EPD specifications: http://www.very-best.de/pgn-spec.htm#16.2
• PGC (Binary representation): http://www.very-best.de/pgn-spec.htm#20.

On Chess Programming

• Dr. Robert Hyatt: http://www.cis.uab.edu/info/faculty/hyatt/pubs.html
• Gerbil: http://web.archive.org/web/20071026090003/http://www.brucemo.com/compchess/programming/index.htm
• REBEL: http://members.home.nl/matador/chess840.htm
• mediocrechess: http://mediocrechess.varten.org/guides.html
• Eliminating rotated bitboards: http://arxiv.org/pdf/0704.3773v2
• Chess Wiki: http://chessprogramming.wikispaces.com/
• Beowulf: http://www.frayn.net/beowulf/theory.html
• Verhelst: http://chess.verhelst.org/1997/03/10/search/
• Mizar papers: http://www.mizarchessengine.com/papers.htm#Chess_papers

Other

• PGN files to use for opening books: http://www.pgnmentor.com/files.html
• Chess standards project: http://code.google.com/p/chess-standards/
• Alternative chesspiece identifier letters: http://www.very-best.de/pgn-spec.htm#17.
• Data on hundreds of chess engines: http://www.playwitharena.com/directory/user.htm#new%20files