Tic-Tac-Toe - Game offers two-player, play against computer, or computer vs computer option. Features three levels of difficulty and saved wins. (JavaScript) - http://ostermiller.org/calc/tictactoe.html
Pig-Tac-Toe - Two player version of Tic Tac Toe game played with pigs. Game requires Internet Explorer 4.0 or higher. (JavaScript) - http://www.yuckles.com/pigtactoe.html
3D Tic Tac Toe - Get four in a row horizontally, vertically or diagonally on one plain or across all four plains. Played against the computer. (Java) - http://home.earthlink.net/~cmalumphy/3d.html
Senor Pobre's Tic-Tac-Toe - Game played against a smart-mouthed virtual chihuahua. (Flash) - http://www.infospace.com/games/game_tictactoe.htm
Tic Tac Toe - Game allows user to specify the height and width of the board, and the number of marks in a row needed to win. Played against the computer. (CGI) - http://boulter.com/ttt/