Stand everyone in a circle.
The leader then says his/her name and then throws a tennis ball to the person to their left. Continuing in one direction each person says their name and passes the ball until it gets back to the leader. The leader then calls out someones name and then throws the ball to them. That player then calls another name and throws, and so on. Once people are getting an idea of names, introduce another ball, and then another as it gets easier.