I'd like to see a plugin that allows placement of blocks anywhere, which you can't normally place. Specifically Trap Doors/Hatches. A way to place them without the requirement of a block on the side of it. I'd even be happy with it if you have to -start- with a block beside it, but then be able to delete the block, and the hatch stays there.
This would be cool. I'd like to be able to put trap doors on top of things, and the requirement of a block next to it is annoying