A small thing that struck me as odd (hi, BTW, i'm new to these forums) is the fact that the screw pump in fact resets pressure.
I find this odd as the Archimedan screw is basically nothing more than a tube with a corkscrew in it. High pressure water on the intake should flow merrily through the pump to the exit, in some cases faster than the pump can actually pump it. I understand why it does this from the way the pump is implemented in this game, but I would sometimes like to be able to make use of pressure even when I use pumps.
For instance I have an entrance in my fort, that is basically nothing more than a pit about 10 z-levels down from the water level. I have dug a pit equally deep under the water, and using some clever digging techniques, I lost a mere 3 dwarves in flooding the pit.
Now I would expect the water to run straight through the pump and up the entrance... but it doesnt.
Again, I understand _why_ but as long as we're tossing out ideas: how about multiple types of pumps?
The normal screw pump as is would be useful for fast water transport for things like, say flooding your fortress due to a minor mistake in walling the pumps in, but could not build pressure (due to the being a tube and all) or block natural water flows, and a gear pump would pump water slower, but be able to build up pressure on the exit side as well, so it would be able to pump water *up* a few z-levels. (not too many, maybe 2 max). Not sure whether this should pump magma up as well, perhaps not.
Additionally, a gear pump would (obviously) need gears made specifically for these types of pumps, giving the mechanic something other to build than the generic 'mechanism' which can be practically anythin at this point. Seen from where mechanisms are used at the moment a mechanism is a lock, deadbolt, gear, bevelled gear, clutch, axle, strut, piston (although not hydraulic, so more of an actuator), ratchet, switch and crank.
Probably these don't all have to be separated out into individual components, but this is a bit too... generic... for my tastes at least.
As far as the suggestions in the FP, i'll sum up my opinion for you to enjoy:
Steam: YAY
Electricity: NAHH
Scopes and massive weapons: NAHH