i know this was posted in the past as a form of Construction Laser and was approved, even though alblaka said he was going to lean more towards to Block Luancher idea. so i would like to run with this alittle.
perhaps have this Block Launcher fire the items in order along your hotbar that are placable blocks? for example: if you had Dirt in slot 1 then it would fire dirt, if you had cobble in slot 2 then it would fire cobble once your out of dirt. however, i'm curious as to if you could have it "place" other stuff as well such as torches. i'm not asking for a mobile flying light source, simply having the torch placed at a long range, that way i could take a stack of torches and fire away and go nuts with it in a ravine to light it up. also, could this block launcher be used for destructive purposes too? such as loading Sticky Dynamite into it to increase the "throwable" range of the dynamite? such as firing it high up at a ceiling or wall to shoot down specific minerals without having to get a mining laser set for Long-Range and accidently blast a hole 14 deep into a wall and open up into an ocean of lava lake, or worse.
also i'd like to see a mode on the Block Launcher to fire Items without placing them. like if someone asks you for torches in multiplayer and they are at the top of a mountain then you could place the stack or torches in your Hotbar#1 slot and fire a stack of torches up to them. or a bucket of water to them so they can place it so you can swim up to where they are.