Hi there, first time poster, somewhat experienced player.
I have graduated from struggling with the varied complexities of fortresses into the fun and amusing portion of the game that is screwing with your dwarves through ridiculous and often dangerous contraptions. My current project is the dwarven escape pit.
The basic idea is this. I have a complex labyrinth of mines underneath my fortress (it's an above-ground stone castle) and I abhor wasted space. I've extended a portion of my castle out over some bare landed, and currently I'm tasking my miners to channel down into the mines, which I have stocked up with food, booze, emergency workshops, stone, and wood. I have also placed beds and seed down there as well.
What I hope to eventually create is a massive tower with a staircase that spires around the main escape shaft. At the top will be a drawbridge with a single lever next to it. In the event of a siege I cannot contain (doubtful, as I have a variety of guard towers, hidden marksman fortifications, and enough traps to slaughter 4 megabeasts, and a hundred war dogs and wolves) the civilian populace will be drafted and led to the tower. My army will do its best to delay the gobboes as much as possible, but they'd be little more then a holding action.
My surviving royal guards will take positions defending the staircase to buy time for any stragglers. I will designate a new meeting area so that the remaining animals will also act as meat shields.
Once the civilians are at the top I will order the lever to be pulled, activating the draw bridge. Taking size into consideration, I will only be able to create a 4x4 escape shaft, 16 civilians at a time.
The drawbridge will retract, plummeting the no doubt terrified dwarves into the pits of my mines, and my backup fortress. At the bottom of the shaft will be a reservoir of water. With the lever pulled, a screw pump will begin draining the pit. The idea is that the water will cushion the impact (I've seen water cushion impacts that would normally break bones, but the drop I'm talking about would gib) and the pumps will empty the reservoir before any dwarves drown. The water will drain into a chamber with a pressure plate set to close the bridge behind the dwarves. Then the reservoir would reset itself while the drained water would be allowed to flood away. Thus setting up for the next set of retreating dwarves.
Any ideas or comments to add to the system? Sorry bout so much text, I'm just really excited for this system. Losing is fun, but making a comeback is more fun.