In the main fortress I'm working on, I decided to create a treasure vault that I'm trying to fill with coins (even though they don't have an in game purpose) and large cut gems. For the entertainment of my dwarves, I'm in the process of creating a room with life sized chess board using microcline and orthoclase furniture for pieces.
However, while looking at the wiki, I got interested in the idea of a fortress prison. I disabled all the leader's labors except for admin ones and architecture. I had 2 miners, a forge & furnace master, 1 grower/brewer/butcher/cook, 1 handy dwarf for mechanics, masonry, & carpentry, & 1 sheriff, who doesn't do much work since there is no one to guard yet. I decided that the 1st wave of immigrants would be the grunt level guards. Anyone who shows up after that will be prisoners, unless I decide there is some plausible reason for them to be part of the prison staff when I look at the migration wave.
I flooded my first prison attempt out with a faulty pumping design, but I've got a 2nd prison ready to go with a central water column that is correctly re-pressurized with a pump powered from a surface waterwheel. The water was key because I decided that prisoners should not be allowed any booze. Along those lines, I decided that a prison riot from tantrumming booze deprived dwarves was more fun than having the prisoner die of thirst.