You are all aware, probably, of the Babolat Pure Drive Play racquet that incorporates sensors and accelerometers to give you feed-back, good or bad!
Sony also has a new device that is available for a few Yonex racquets in Japan at this time.
Now there is another device, sort of like a vibration damper, that will give you feed-back on your shots, good or bad. This is a pre-production announcement so here is a link if you want to investigate it further.
http://www.shot-stats.com/?token=3cd4b8cfc0f75551ed9d79c86bb7aeeaa7b67174
I have no first hand experience with this device but it relates to tennis so it may be interesting to find out more. I am anxious to get my hands on one!