A hand-held medical diagnostic device
It seems like Star Trek not only entertained us, but helped scientists with ideas about technology. If you remember the diagnostic device on the show, you know how beneficial would be to have it today. While a similar device is being developed, we can take the infrared thermometer as a modern example of something that everyone has the chance to use at home today.
Actually, one of the X-prize challenges:
https://en.wikipedia.org/wiki/Tricorder_X_Prize
#9 thats not the only thing about that movie that already exists
stun gun