So.... we have community gardens now...
How about a community Dirt Pit? Maybe it's a different type of patch that nothing grows in, or maybe it's a message that says 'there is not enough light for things to grow here' when you try to plant in it. Maybe we get a new powder that causes erosion and makes the dirt refill faster.
How about Community Pens? The room could hold a certain number of player contributed pigs that can be fed... and plopped (or squeezed). Maybe it has a mesh floor the plop falls through (hole in the floor style... *use* that bug, dude) making for easier collection. Perhaps while you're in there you lose mood and/or energy Wintry Place style because of the stench.
And finally.... I still want a Composting Facility... either as a machine or a community place. Organics + Dirt + Plop + Water + Work = Compost. Perhaps the compost is something you add to the gardens for a higher/faster crop yield.