I always wondered why bat wings are not in the game, but this suggestion would remove the uselessness of bats and make them viable mobs
Bats would drop bat wings. These wings could then be used to make at least 2 potions: Potion of hearing and potion of blindness. Since bats are generally known to have excellent hearing and poor eyesight, these potions would make perfect sense.
Potion of hearing: This potion would detect creepers coming up behind you and other mobs/players. Perhaps a hissing sound from creepers would be their indication they are around, other mobs perhaps just amplified noises they make.
Potion of blindness: This potion would render the mob blind, and walk around without attacking for a set period of time. If used on a player or if you are affected, the screen goes black or EXTREMELY dark. Cure could be potion of night vision
As for bats, they would inflict minimal damage, perhaps have an upgraded version of a bad that would inflict a poison status for a shot period of time. XP could be 1-2 or 1-3 for rabid bats. Wing drop could be 1-3.