I've merged the Friendly-, Stupid- and MiniCreepers together!
Just start minecraft with the installed mod once, then edit the properties-file.

Default:

MiniCreeper=true
StupidCreeper=false
FriendlyCreeper=true

Friendly Creeper:
Creeper explosions don't destroy blocks anymore, but the player still get damage.

Stupid Creepers:
They do nothing and they look to the sky 'til you kill them
If you touch one, it will just follow you (don't hurt you).

Mini Creepers:
Are small and sweet, but be aware. Once you killed a normal Creeper, there will appear 6 MiniCreepers
MiniCreepers deal only a half of the damage, leaving smaller holes in the environment and have less life.
Take a choice, let a Creeper explode or kill him and face 6 MiniCreepers

No modloader required!