For when you get tired of your fort and want to go out with a bang.
Personally this is my best, though it was semi-botched up by STUPID DWARVES.
Only 5 dwarves are left in my glacier fort. I settled on a huge 28-level-tall volcano, but there's no way to get more food. I'm hoping I can get this thing built before we all die of thirst.

Lever 'A' lowers the bridge (arrow). Note that bridges don't provide support.
Lever 'B' destroys the only thing holding up the whole platform, 3 supports underneath. Everything is made completely of ice and is dangling 16 stories above a pool of magma.

This is how it plays out:
http://mkv25.net/dfma/movie-907-elaborateglaciersuicideOnly 3 dwarves were actually on the platform, one was on the threshold and fell when the bridge was retracted, and a miner escaped the fate completely. No-one was where they should be, because apparently they
refused to move to a new meeting area inside the square area. They just stood around the old meeting area, being stupid. Drafting them didn't work. I even put their beds on the platform, but when they woke up they went straight back to the old meeting area...
So they all hit the ground
around the magma pool. Lame.