This is a very simple passing drill that looks harder than it really is.  It teaches the players the importance of good crisp passing, hand-eye coordination, peripheral vision and teamwork as if one piece breaks down, the entire drill is ruined.  It is also a very good conditioning drill as the pace picks up.

Eight or more players evenly divided on four corners of the half-court.

This drill is best learned with only one ball, but is best run with two or more. Example shown is with two.

Begin with balls on opposite corners. (1 & 5)

At the signal, both players give good passes to the corner to their right and follow the pass 1/2 the distance before cutting to the opposite corner.

The receivers (3 & 7) immediately return the pass to the players cutting to the opposite corner (1 & 5).  As the cutters receive the ball, they then pass to the corner opposite from where they started.  When 3 & 7 pass the ball, they follow their pass and cut to the opposite corner.

Just as in the last sequence, pass the ball to the cutter.  The cutter passes the ball to the opposite corner, and the passer from the corner follows and cuts.

Overview:
This is a simple drill as each player is basically sprinting to the opposite corner while passing, receiving and passing again.  For an overview, follow one ball around the court.
1.  Pass the ball to the right and follow and cut.
2.  Receive a return pass and then pass to the opposite corner
3.  Sprint to the end of the line in the opposite corner.
Change the flavor by changing directions, changing types of passes, and adding balls.
A very good pre game and start of practice drill.