Dungeons and Dragons Prestige Classes

For some reason, I find it fun to design prestige classes in the game of Dungeons and Dragons. For those of you who are not aware, prestige classes are additional 'add-ons' to existing classes that the player can obtain. For example, a fighter would be a class; a Fighter of Justice and Evil Pie would be a prestige class. Prestige classes require certain amounts of levels and what-not from the existing 'main' classes. For example, you would need to be a level 6 fighter to even attempt to become a Fighter of Justice and Evil Pie.

Firstly, does anyone who has a clue of what I speak know of what I am speaking about? Secondly, I am trying to think of a better idea for a prestige class. Thus, like a parasite, I have come to suck the thoughts from you .

The existing 'usual' classes are:

Fighter
Druid
Wizard
Cleric
Ranger
Monk
Paladin
Rogue
Bard

Can any of you think of good names or ideas? Such as a Cleric that can turn himself/herself into a dog at will, a paladin that is immune to fire, etc...

What a bizarre concept, .

So, any thoughts?