Like the leather drop from the cow trophy, thought some additional effects could be fun.
Each of these effects would be equal to a long duration potion, so 8 minutes, and requires 1000s cooldown - have to save cooldown state when block is broken to prevent exploiting.

bat - Grants flight
wolf - Grants nightvision
sheep - 1 block of wool
ocelot - Grants speed
silverfish - grants invisibility
spider - surrounds area in cobwebs
zombie - gives nausea and 1 rotten meat