I think a chest with a few potion ingredients would be quite nice. The cat could also be a trophy thing. You know like a fully black cat with yellow eyes that only spawns in a witch's hut and can be tamed after you kill the witch. It could also have a slightly larger creeper deterrent radius.
This. Every bit of it. Almost.
The black cat (as opposed to the existing tuxedo cat) would not only have a unique skin, but also have altered AI. If tamed to you (since you could not tame one while it is tamed to the witch it spawned with) it would follow you always, ignoring you if you told it to sit and stay. It would, however, keep a greater distance, simply staying within 10 meters to keep an eye on you. It would teleport to the highest point within 10 blocks of you (including 10 block up max) and keep looking at you always. Creepers ignore it, but undead mobs are repelled (voodoo cat) and it will TP to your position instantly if you are struck by an undead mob. The voodoo cat is also immune to all damage, unless you try to strike it while there are no hostile mobs near. If you do, it will TP around and attack Enderman-style until it is low on health and then vanish. From then on it will spawn at a random location roughly 20 blocks from you whenever you are in the dark or it is night, staring silently at you and then vanishing if you come within 10 blocks of it.
This. Every bit of it. Almost.
The black cat (as opposed to the existing tuxedo cat) would not only have a unique skin, but also have altered AI. If tamed to you (since you could not tame one while it is tamed to the witch it spawned with) it would follow you always, ignoring you if you told it to sit and stay. It would, however, keep a greater distance, simply staying within 10 meters to keep an eye on you. It would teleport to the highest point within 10 blocks of you (including 10 block up max) and keep looking at you always. Creepers ignore it, but undead mobs are repelled (voodoo cat) and it will TP to your position instantly if you are struck by an undead mob. The voodoo cat is also immune to all damage, unless you try to strike it while there are no hostile mobs near. If you do, it will TP around and attack Enderman-style until it is low on health and then vanish. From then on it will spawn at a random location roughly 20 blocks from you whenever you are in the dark or it is night, staring silently at you and then vanishing if you come within 10 blocks of it.