I mentioned before how you can use the game of Newcomb to work with inexperienced players. You can use it to teach court movement, positioning, and things like that in a volleyball-like, but slower speed situation. At the HP Coaches Clinic they did something similar, but for a more advanced purpose.
The coaches lowered the net down to just about head height for the average player. The demo athletes then played a co-operative 6 v 6 game with no jumping. The third contact was set over. Basically, it was all the movements you normally see in volleyball. The players just did not jump.
In this particular case the focus was blocker movement. The coaches watched the middle blockers for proper focus on their reads and their footwork. It was a way to give those middles lots of reps without burn out.
Thinking more broadly, this is an exercise that can serve a number of purposes. It could very easily be a warm-up. It includes lots of volleyball motion, just done at a lower intensity level. You can tick up the intensity if you make the 3rd contact be a down-ball.
Of course, you can also get rid of the cooperative aspect and make it a competitive game. That speeds things up, demands more movement, and introduces more problem-solving elements. It makes reading more game-like, and gives you increased opportunities to focus players on specific aspects of their play while still is a lower intensity situation.