Nothing too spectacular in my fort, though the three fold ballista battery entrance corridor is coming along nicely... basically three three balista batteries each pointed down a 3 wide hallway that is 100 squares long past the outer fortifications such that anyone entering the fort must first walk 100 tiles towards the first battery, move into the second corridor and walk 100 tiles with their backs to the second battery, then turn again and walk a final 100 squares towards the final battery before reaching a ramp that brings them up into my fort's courtyard. 300 squares of withering ballista fire will await anyone bold enough to dare invade my fortress, and that's assuming that I decide not to use the magma-flood chamber which I am also constructing (it's designed to pump magma up through floor grates rather than pour it in from the top; rahter than a quick and sudden death by magma shower they will be treated to a slowly rising wave of heat as the molten rock slowly rises under them and begins to penetrate the iron grates that this will be floored with.)
The other work of dwarven ingenuity is the airconditioning system (a nine square mist generator) for my dining hall, which hit a few snags because the water is, for some reason, leaking around in the overhead area, probably as concequence of having had it hooked up to a large water source... good thing I set the priming pump to be dwarf powered, the pump operator got tired before enough water accumulated to start escaping in the dining area as well. I'll probably set up a fast repeater to make the priming area only deliver one chunk of water every second or so; less mist, more safety.