When new migrants come onto my map, they are sorted into useful and useless.
The useful are given luxurious accomodations, ushered into the fortress with much celebrity, escorted by the Iron Guard. Useful being defined as any dwarf with skill in a job I currently have need for, useless being defined as everyone else.
Once the useful are taken care of, I turn to the useless. If I need recruits for the Iron guard, the useless are handed a wooden or silver training weapon and a suit of leather armor. They are then placed in squad with the Training Master, who is a grizzled old champion hammerdwarf with an artifact lead warhammer and masterwork iron platemail. They stay in training with him until injured so badly they cannot keep fighting, at which point they are dragged off to the barracks. Assuming the injuries are non-permanent, they are officially designated an Iron Guard recruit and placed in the training squad with other recruits until they are promoted to champion status, at which time they join the Iron Guard.
When I do not need recruits, the useless dwarves are given a pick and sent into the Hall of Failure, a large cavern excavated in the side of the mountain. They are made to dig a small 3x1 room from the hall, make a statue and coffin at the masons shops there in the hall, set up their own statue and coffin, and then use a piece of stone to seal themselves into the tomb with a wall. Once they die of starvation and neglect, the tomb is opened briefly to strip the useless dwarf of his clothing and pick and to inter him in the coffin he made for himself.