This can have many advantages, for instance it would be so much easier to have a slime farm, and if they dont despawn when you have befriended them, then that'll make your slime farm permenant!
Well what if you dont want a slime farm? What if you want to make an army of slimes that will fight for you and protect you when you need it? That would be even cooler. You could mabe give them special slime armor so they dont die as easily.
You could even mabe ride the slimes into battle?
To tame a slime you need to give them Slime Food:
This will make the slime follow you and be your loyal minion. If you press (E?) then the slime/slimes will stand still, this makes things easier when your moving them around.
To heal a slime you give them Slime Potion:
EDIT: Gives 4 Potions not just 1
This will heal all the slimes wounds during a battle so they wont die.
This is how you make Slime Armour:
EDIT: it wont look like a helmet, will have custon icon.
This armour can be made from leather,iron,gold and diamond. Diamond being the strongest of course.
Now that you have seen my ideas, please make this mod
ALL IN RED WAS ORIGINAL POST
This may seem like a stupid idea but since slimes are "so rare" I think they shouldnt despawn, so you could have a farm/home of them
If not mabe you feed them something to keep them from despawning? That might be better because you wont over croud your world.
EDIT: OK since I'm getting quite a bit of support on this I made a little support banner
EDIT2: Support banner too tall...DAMN IT gonna re make it...
EDIT3: Should be fixed...