First Internet Backgammon Server (FIBS)
The longest running server and a popular site. A rating system ranks players according to their performance. Hosts regular tournaments.

Chicago Point Backgammon Links
With over 450 sorted and annotated links to the best resources on the Internet to learn about and play the game of backgammon.

Gammon Empire
Online backgammon playsite. Play for money or for free.