OtherZombies
My plugin, OtherZombies, allows Baby Zombies, Giant Zombies, Zombie Pigmen, and Boss Zombies to spawn naturally.
Everytime a Zombie spawns while this plugin is running each type of zombie has a chance of spawning based on the percentages set in the configuration file. All percentages are CONFIGURABLE! As of the 1.0 Release you can now disable mobs by setting their percentage to 0 in the configuration file. You can use the percentages to control the amount that a type of zombie spawns.
Zombie Types
Boss Zombie
A Boss Zombie has 11.5x the health of a Normal Zombie, Gold Armor, and a Gold Sword (Plus 4 Hours of Fire Protection :P)

Giant Zombie
A Giant Zombie is a HUGE version of the Normal Zombie we all know and love

Baby Zombie
A Baby Zombie is a mini version of the Normal Zombie (They are so cute!)

Pig Zombie
A Pig Zombie is a Hamtastic version of the Normal Zombie (I'm hungry now...)

To Do
1. Configurable percentages
2. Disable Mob Types
3. Add more Zombie fun
Upcoming Features in [Release 1.1]
1. A command to reload the OtherZombies configuration file ingame.
2. Baby Pig Zombies
3. Making the zombies only spawn from natural spawns (Zombie spawn eggs won't spawn the different ones, same with /mob)