During one of the on-court sessions at the HP Coaches Clinic, someone presented an idea about hitters attacking the block. They put an antenna on the net about a meter in from the left side pin. Basically, it defined the zone in which the OH normally attacks. The hitter then had to hit the ball between the antennae. That obviously makes it harder to hit around the block. This forced the hitter to work the edges of the block. Or they could attack seam, if that option was available. The blockers took line or cross to work on things more narrowly.
This sort of thing can be used in the Pin Hitter Challenge game they demonstrated at the clinic, if you have two sets of antennae. It also works in the Hitter Tourney drill, the Hitter vs. Hitter Challenge or High Ball to Receive games. Basically, use it in any game or drill with hitters against blockers with lots of sets to the attackers in focus.
Of course training the attackers in this fashion also benefits blockers as well. They can work on good hand position and angles to avoid hitters tooling them.