Mud Runner
No need to finish internal drywall corners free hand. The power-assisted MudRunner will do it for you with little effort. A twist of the wrist starts a continuous flow of joint compound to the corner finisher or mud head, and a twist back stops the flow immediately. It holds twice as much compound as a standard 8-inch corner applicator. Cost: $750.  TapeTech Tools.  800-426-6256.