Ascension Technology Corporation - makers of a line of magnetic, optical and inertial trackers, including Flock of Birds and a wireless version called MotionStar

InterSense - offers several motion capture and tracking systems, based on inertial and ultrasonic technologies, including the InterTrax line

Microscribe - a line of 3D digitizing devices that capture the physical properties of objects and translate them into 3D models using points, lines, polygons, splines or NURBS. From Immersion Corporation.

Motion Analysis Corporation - makers of optical motion capture systems, including the Realtime HiRES Motion Capture System, which simultaneously captures and displays 3D data; and Solver, ExpertVision3D and Real-Time 3D systems, full-body capture systems 

Polhemus Navigation Sciences - developers of motion capture and magnetic tracking tools, including the real-time StarTrack wireless system

Shape Tape -  a flexible, wearable plastic ribbon that uses software to create 3D computer images and data sets of shapes, based on bend and twist information from fiber optic sensors along its length, from Measurand Inc.

SimGraphics - developers of the VActor System, which animates virtual characters from the motion-captured performance of human actors in real-time