That blow gun from District 9. The one that pushes a person through a wall, or anything else for that matter. It would be pretty neat in a DM. Pushing someone 100 meters in one shot. Or shooting a wall and making a 6×6 brick hole. It would be awsome if it shoot 2 projectiles with a 50 to 100 ms delay. The first colliding with bricks, the second colliding with players. That way you could actually launch a player through a wall.
If you have seen D9, then you'll know exactly what I mean.