You can also do a ring game tournament. Mikeyfrost has posted info about a ring game format using poker chips; I tried it in a local pool room for a while and it worked nicely. We played 10-ball with different starting chip counts for A, B, and C players (I think we used 10, 15, and 20 respectively); maximum of 5 players per table with table consolidation occurring each time the total number of players decreased to a number evenly divisible by 5; starting ante of 1 chip per game with ante doubling each half-hour. We played call shot 10-ball, rollout at any time, and pass back after a foul, but you could use whatever rules you like. I think I still have a complete set of rules for this format along with a payout schedule if you are interested.
Aaron