I must say, for years I had been a firm believer in the DeWalt Cordless Drill, but this past year I was introduced to the Bosche 14.4 BruteTough Drill Driver, which is built like a tank. Needless to say, I am now a huge fan of Bosche.
For stage managers though, I must say that the 12V Litheon Drill Driver by Bosche is perfect. It charges in 15 minutes for approx 100 screws worth of battery life. It is small enough that it can fit in your pocket, and has a decent enough amount of torque to it.