There are some very creative solutions and products that have already been developed using Kinect as the main interaction tool. Meanwhile, talent designers are also creating some other motion-sensing systems that can totally replace Kinect in interactive applications. Here is a very incomplete list of them:
KinÊtre: This can be used to create playful 3D animations using realistic deformations of arbitrary static meshes with Kinect (by Microsoft Research), and can be found at http://research.microsoft.com/en-us/projects/animateworld/
KineMocap: This is used with multiple Kinect devices for accurate motion capturing and can be found at http://www.kinemocap.com/
FaceShift: This uses Kinect as a replacement of motion capture devices for facial animations, and can be found at http://www.faceshift.com
ReconstructMe: This is a real-time, 3D reconstruction system that can be used by moving Kinect around freely to collect data, and can be found at http://reconstructme.net/
So Touch Air: Using this, you can create impressive air presentations that can be controlled by moving your hands in the air; it can be found at http://www.so-touch.com/?id=software&content=air-presenter#
OMEK: This provides middleware and tools for easy gesture recognition and tracking interfaces, and can be found at http://www.omekinteractive.com/
SoftKinetic: This provides 3D gesture-control solutions for consumer and professional markets, including its own time-of-flight, depth-sensing camera and the iisu SDK, and can be found at http://www.softkinetic.com/
PlayStation Eye: This is a digital camera device for PlayStation 3; it includes computer vision and gesture recognition features and can be found at http://us.playstation.com/ps3/accessories/playstation-eye-camera-ps3.html
Xtion Pro: This is another 3D depth camera from the OpenNI community and can currently be purchased through ASUS at http://www.asus.com/Multimedia/Xtion_PRO_LIVE/
LeapMotion: This can be used to record and use natural hand and finger movements to precisely interact with different devices, and can be found at https://leapmotion.com/