Functional Training Workout using Medicine Balls is one of my favourite ways of training my clients.  Back in 2002 I walked into Esporta Chiswick Park, and like many clubs at the time the medicine balls sat next to the ab rollers (remember those?) untouched and unloved.
Luckily over the following 18 years the medicine ball became better designed and more used in workouts.  Crossfit definitely pushed the use of them even more than the general introduction of functional training into the industry. 
These are some of my favourite medicine ball exercises, filmed six years ago with a cool friend.