I, in a humble manner, submit the following suggestions.
1) Dwarf Post Office - This would go well with the army arc by allowing you to send and recieve mail from other sites on the map. You could recieve warnings from abstracted scouts of your fortress warning of incoming armies/traders. You could send mail requesting aid from other dwarf fortresses/human towns ect or to tell them to STOP sending caravans if that is what you wish. You could send letters back home requesting certain nobles NOT be sent to your fortress in the event of death of existing nobles. Like wise you could use this to request nobles be sent to your fortress once certain requirments are met, instead of having them just show up (This way players could decide if they want a certain noble or not instead of trying to devise insane ways of keeping them from ruining the game) Still, these requests could all be refused and nobles could show up any how.
2)Dwarf Immigration Office - This Office would be the first stopping point of all dwarfs that come to your fortress once it has been built. Here you can keep track of how many dwarves are coming to your fort, what their skills and abiltiies are and what they are set to do. With this office you could set up standards by which dwarfs could be rejected or allowed to enter. You could set it to set incoming dwarfs to do certain jobs. (Say the next 3 immigrants are farmers, the 2 after that are axe dwarfs, the next one is a black smith) You could use it to keep track of your fortress' draw on immigrants so if you're killing a lot of nobles or a lot of people have been dieing you can see here that people are afraid to come to your fortress. Of course nobles might well totally ignore this office and walk straight on in past it. This is more for the serfs
3)Dwarf's With Disabilities Office - Those dwarves that are injured so badly that they will never heal can come here to special assistance. They can be given specially trained dogs that can help them with their lives and medical treatment which could restore them to their former glory if they have lesser injuries. Maybe once magic is in dwarfs could come here to get fully healed of their injuries. Also dwarve in foul moods could come here to get counciling O.o hehe
4)Dwarven Recruitment Office - This could be used to enlist dwarfs into the army on a volentary(SP) basis. In this way you could recruit dwarves that have other skills without giving them bad thoughts. Also you could use this office to build a guard force that is only active in certain situations so when you're under siege you go here and activate the guard. Then all the dwarves you've recuited into the guard are drafted into the military with preset weapons and armor and go to their preset guard stations. This way you can lower the standing amount of soliders but still be prepared in case of an attack.
Anyone else have any serious ideas for dwarven civil service buildings ? :p