GNU Backgammon - Plays and analyses backgammon games and matches
BGBlitz - BGBlitz2Go, a strong playing Backgammon for mobile phones
Nextgammon - Your Ultimate Online Backgammon Destination!
NetGammon - Play a free online Backgammon game against the computer or jump into a Quick Match.
BGLightCE - BGLightCE, a Free Open Source Backgammon for Windows and Windows Mobile or Pocket PC
Absolute Backgammon - Download Absolute Backgammon for Mac free. Ready for a fun game of backgammon! Superb graphics, feature packed, easy to use