Once you get to a particular point, you have a surplus of dwarves. Lest you cull them by drowning them, burning them, dropping them in pits or throwing them at beasties, they'll have no real job in the fortress.
So, lets make up some job titles for those idiot, glory-stealing, good-for-nothing, late-arriving snotlings that dare to call themselves dwarves!
Dairymaid - The immigrant that brings a cow is the dairymaid, reguardless of gender. They have to look after the thing and sleep in a little hut next to the pasture.
Gladiator - Soldiers, each trained in a different weapon, they are pit against captured foes for the entertainment of the masses in a arena.
Ratter - You know that one dwarf? The one that is followed by a sea of writhing cat? Send him out into the wilds to rid the world of vermin. He can only wear leather and weild daggers.
Pirate - Ah, the pirate, or indeed, for those with better intentions, sailor. Build a moat around an island, then build a structure not unlike a crashed ship. Fill the island full of your loonies and give 'em lots of rum. The best fighter is called a Captain. Build catapults and the like along the "ship".
Foreign Legionnaire - Build a watch tower far from your fortress, fill it full of veterans. Their leader is a General, called de Négrier for bonus points.
Doomsayer - Every fortress needs one, pick that depressed dwarf over there. No, that one.
Butler - A peasant who's only job is to clean and perhaps cook, he works for a noble and lives in a room beneath the noble's quarters.
Barber - The hairdresser of dwarven kind...may actually come into play soon. Toady One thinks of everything. He gets a large room and a barber shop. Have four of them for a barber shop quartet!
Gardener - Clears out the weeds from the fortress gate. A gardener's duties also involve fighting baboons bare handed and shooing away elephants that try to stand on the roses.
Lawyer - Speaks the case for imprisoned dwarves, surprisingly, they don't win many cases.
Monk & Nun - A peasant dwarf that really digs (pun!) their god becomes the local monk or nun, as more worshipers turn up you can add a few monks and make the original an Abbot. They live in a huge monastry deep in the earth or alternatively, on a mountain top. You could even create rival monastries!
Saint Nicholas - A dwarven santa! A expert toymaker and all round nice guy. Unless you're naughty, he is a hammerer after all. Oh, and don't mind the caged elves, they're his helpers, honest! Bonus points for pet raindeer.
Lighthouse Keeper - Build a tall tower on a cliff and keep this guy stuck inside it day and night. Bonus if you are in fact no where near the sea.
Knocker - A unimportant, I mean sacred, miner, that is sent to dig first before the rest of your mining crew to test for water, magma and monsters.