If you believe in the old golf saying that you "drive for show and putt for dough" then you might consider the DiXX Digital Training Putter from Adams Golf
an investment. The putter is a computerized training system that can track swing path, face angle, speed, tempo and impact position and display the information on an LCD screen on the club. The data can them be analyzed. The club also comes with a practice weight for recreational use. As you might suspect, it's not USGA approved. It sells for around $400.