Gamer Cafe Software. Strong neural-net program. Three skill levels. Single game or match play. When you register, you get a printed manual with tips and hints from the author.
Sound card is recommended.
David C. Oshel. An expert level player, large bearoff database. Player version plays backgammon against you and calculates a rating for you. Champion version performs rollouts with variance reduction, lets you import matches played on the Internet. Newsgroup postings about Snowie.