The introduction of Dung presents us with a new block that should be reasonably challenging to procure, as well as more finite than most blocks (side-idea: domesticated titan beetles could produce dung at random intervals?). Here are some ideas regarding usages for dung:

1: Farming
An interesting mechanic I thought up would be to bury Dung 1 block below farmland. This would give the farmland above a ''boost'' to growth speed (nothing too crazy, 1.5x or less) of the crops growing on it. After a random amount of time, Dung used in this manner will transform into Dirt.

2: Botfly distraction
Dung that is exposed to air could perhaps attract Flies and Botflies within x blocks from it. This would give players an interesting tool to somewhat control the fauna around their house. Aggroing on the player takes precedence over this effect.

3: Eternal flame
Could function like netherrack in that fire on top of it burns forever. Would be fairly interesting I think, nothing too crazy.

To be updated as I come up with things!

Another source of them: dung beetles! Could be found rolling dung around, and they fling the player away to defend it.

Potential use for it: to grow a special kind of mushroom (like the way nether wart requires soul sand to grow).