So I just read a large amount of the improved farming, rebooted agricultural revolution.
http://www.bay12forums.com/smf/index.php?topic=76007.msg1920005#msg1920005 and it gave me an idea that could end up being a bit of fun, and satisfying part of the goals of that thread. This is not to say that it is any sort of a solution for the problem stated in it.
My idea was one for underground garbage dumps that would be set up with a chute channeled downward that all your garbage would go into, and when it reached the base floor of the dump it would scatter and what not into a cavern, this gets rid of garbage obviously, but instead of it just rotting away, it turns the cavern into a sort of deranged wonderland that produces its own natural food/plant sources that could be gathered by your dwarfs. But plants would not be the only thing that would grow in the pit. New (or old) monsters and creatures would form from the muck in the pit. So this pit would now create food, monsters, and random creatures. <overall it would just be a new source of fun and diversity.
For the most part the creatures that would grow from the pit would be rather innocous and usefull only as pets, pests, and short term food. but rarely a creature would form that would be dangerous, Such as a Blob or a fungus behemoth(wich would have a building destroyer capability.
The pit itself would have to be rather large to start dumping in order to hold all the garbage. The ground would become coated with a slick ooze after a while or after a set amount of garbage had been dumped into it. It could act like a self replicating mud.
And a new job could be created for it, Pit Harvestor! Pit harvestors would be skilled in not slipping and sliding on the ooze and avoiding any monsters or beasts in the pit while still harvesting all the good parts of the pit.<this of course would be a fairly nasty job and only suited for very few dwarves.
Of course you could just wall off the pit and have it as a simple garbage dump and not know any thing about whats growing within it. Maybe the floor ooze itself chews away at the rock and makes the cavern bigger(to a set size as to not become impeding)
Who knows maybe the ooze will create an intelligent monster man that starts its own civilization on the refuse of your dwarves.
Bonus points for creating multiple chutes for the garbage to go down.
Sorry if post is repeat at all. I did search found nothing I considered similar.