Freethedice.com
Long-running website with all forms of yahtzee games, including regular, painted, triple, tournaments and player-created variants, with small community and chat. Requires free registration.
Due to ABUSE/SPAM, until the new BBOGD is here. Reviews are being reviewed before being displayed.
I play farkle and yahtzee at this website every day, it's really fun and there a bunch of tournaments and other people to chat to between and during games.
