Macintosh

Chessmaster 9000 Mac
[ $40 commercial] Grandmaster strength, many training features. OS X 10.2+ and DVD drive required. Released Dec. 2004.
http://www.feralinteractive.com/?game=chessmaster9k&language=english&section=

ChessPuzzle 2
[Free] OS X Dashboard ChessPuzzle Widget [OS 10.4 required] with 6,000 puzzles and Sjeng chess engine
http://www.applepi.com/chesspuzzle/

Crafty 14.11B
[Freeware] Version of Crafty with code added so that ExaChess can be used as a GUI interface and computer-computer umpire.
http://www.exachess.com/downloads.html

Crafty Mac 18.08 text
[Freeware] Master strength chess engine, text interface only. Updated March 2001.
ftp://ftp.cis.uab.edu/pub/hyatt/macintosh/

Gambіt 1.01
[Shareware $20] Mac OSX Front end to Crafty with PGN browser. Updated 12-13-05.
http://www.aqueoussoftware.com/gambit/index.lasso

Glaurung and Scatha
[Freeware] UCI GUI with two engines: Glaurung (normal chess), Scatha (Glinski's hexagonal chess), requires OSX 10.3.9+, updated 7/13/2007
http://www.glaurungchess.com/

GNUChess
Freeware download, expert-strength Mac chess program.
http://www.tim-mann.org/gnuchess.html

HIARCS 11.0
[Commercial $50/$100] Strongest Macintosh chess program, in UCI engine form for Mac OS/X. Single and multiprocessor versions. [Out Apr. 2, 2007]
http://www.hiarcs.com/mac_chess_hiarcs.htm

HIARCS 7.0
[Commercial - $48] Macintosh OS9/Classic version of a former world champion chess program.
http://www.hiarcs.com/mac_hiarcs.htm

j2chess 2.8
[Freeware] Simple OS/X chess game / PGN viewer in Java. Updated March 2007
http://www.j2chess.com/

MacChess
[Freeware] Master strength freeware program, ExaChess compatible, and with English/German/Dutch/Italian versions available.
http://members.aol.com/macchess/

MacChess - chess on Mac
Lists software for Mac OS X, classic, X11 and pre-OS X. Includes information for compiling and configuring X11 and XBoard based applications.
http://www.internetcontact.be/~macchess/

MacUpdate: ChessKing 1.0
ChessKing 1.0 - Challenge a friend to a game of chess.
http://www.macupdate.com/info.php/id/201

MacUpdate: ChessMate 6.3.5
ChessMate 6.3.5 - Play chess against your computer or friend.
http://www.macupdate.com/info.php/id/202

RChess 2.2.3
[Freeware] Chess playing program with many easy levels for beginners to win against.
http://www.macupdate.com/info.php/id/10343

Screamer
[Freeware] Master strength program, also works as ExaChess engine.
http://hyperarchive.lcs.mit.edu/HyperArchive/Archive/game/brd/screamer-chess-57.hqx

Shredder
Commercial [ $30-$100] The Macintosh version of the 2005 World Computer Chess Blitz champion. Downloadable Demo, Universal bineary. Updated 2006.
http://www.shredderchess.com/mac.html

Vanessa Chess 2.1.1
[Freeware] This is a multi-document, multi-threaded chess application for Mac OS Classic PowerPCs ( Mac OS 8.6-9.2)
http://www.tucows.com/preview/205782

Vektor3.2.2
[Shareware-$19] Voice command and voice output options, adapts to the user's strength. Exachess compatible. Requires OSX.
http://www.schubert-it.de/vektor3/