Someone already suggested wheelchairs about a year ago, so I hope I may be excused for bringing up the subject again, but I've had some thoughts about them that might be fun.
So I've got a dwarf with a bad lower-spine injury who, I'm told, will never walk again. But there's nothing wrong with her upper body, so I'm thinking that if one of my other dwarfs could build her a wheelchair, she'd be able to be a reasonably productive member of society again -- if you get over the Victorian wicker-chair-and-four-casters idea, and think of something a little more like a modern wheelchair, you get something that a dwarf with working arms can push around on her own.
So I'm thinking it could start out something like this: you build the wheelchair out of wood at a carpenter's shop or metal at a forge, and it's stored in a furniture stockpile. (I don't see a need for mechanisms: chair, four wheels, two axles, and you brake by grabbing hold of the wheels real hard.)
Once the chair's built, I'm not sure how would be best to go about assigning it to the dwarf who's meant to use it; maybe that could be automatic, because any paraplegic dwarf can use one, and you probably don't have too many paraplegic dwarfs in your fortress unless you've been having a lot of fun lately. In any case, once the assignment's made, a dwarf who's not otherwise occupied would carry the wheelchair from the stockpile to the injured dwarf's bedside, and load the new owner into the chair.
From that point, the newly wheeled dwarf is up and about with most of their ordinary capacities, albeit somewhat slowly, and perhaps without agility bonuses being applied to movement. (Or possibly with strength bonuses taking their place? Wheelchair agility is, from what I gather, pretty much all in the upper body and arms, after all.) I figure the wheelchair could go into the dwarf's inventory, which if it's heavy enough might slow movement speed enough all by itself; not only that, but, just as a very strong person can move a wheelchair as fast as an able person can run, a dwarf of sufficient strength could overcome the weight penalty of the wheelchair and get around mighty quick indeed.
Of course, there's at least one big caveat to consider: wheelchairs can't manage stairs, so you'd need ramps alongside your stairwells to provide wheelchair accessibility, and probably other accommodations as well -- for example, I can imagine it being impossible to squeeze a wheelchair through a diagonal passage, so you'd have to plan workshops and other areas accordingly. I don't know about you, but that certainly appeals to my psychotic obsessionsense of fun.
It also occurs to me that, like how up/down stairs pose a slight risk in that unconscious dwarfs will fall down them, ramps might have to be carefully built to prevent unconscious dwarfs rolling downhill to their deaths. While we're on the subject of risk, what happens when a wheelchair dwarf and a walking dwarf meet in a one-wide tunnel? Possible yellow wounds to the walking dwarf's feet from the wheels going over his insteps, that's what. (Crunch!) And, if the wheelchair is an inventory object, it might get damaged in a fall, or similar, at which point the formerly wheeled dwarf would be out of luck until another wheelchair could be found, or failing that a rescuer to carry the unfortunate back to bed.
There are other benefits, too! In addition to restoring most of an injured dwarf's capacity to work, a wheelchair like this one would also give such a dwarf the ability to get to food stockpiles and dining areas on her own -- and, most importantly, the ability to imbibe sweet, sweet booze. In fact, I can even see a place in the military for a wheeled dwarf; do you need the use of your legs to, e.g., put a crossbow bolt through a goblin's eye and out the back of his skull? And think of the shame it will bring every goblin who learns that your fortress can stand off massive sieges without even needing soldiers who are able to walk!
So what do you think?