Some fun and easy dice games include 100 and Triples. In Triples, each player rolls three dice, and the first person to roll triples wins the round.
Any size group can play 100. Each player takes a turn rolling a pair of dice. If someone rolls a double, that person counts to 100 out loud as quickly as he can. While he is counting, the other players keep rolling the dice. If someone else gets doubles, the person counting stops counting, and the new person starts counting. If someone gets to 100 without someone else taking over, he wins the game.