This would mean the addition of 2 new items. The first would have to shoot some sort of laser probably only when powered with red stone. The second would be activated when hit with the laser. When activated, it will power redstone wire allowing you to create crazy traps. The laser flow can be interrupted by players, mobs and other blocks. The laser can go through glass, water and other opaque blocks.

It seems simple when written, but might be difficult to code. Just something I wanted to share with the world... of Minecraft.