There are several initiatives that focus on multi-user interaction on a single (large) screen. Dutch start-up Wunderwall has developed a properietary system that uses the gyro mouse for interaction on a large projected image. Another solution comes from Megaphone: use your phone as controller. Their focus is on gaming at public places (combined with advertisment), but there is no reason why such an approach would not work in collaborations (office meetings). So give your meeting participants finally a chance to show off their mobile phone in a meeting by letting them vote on your proposal!