Paladins were/are pretty good strat/scholo tanks on account of hitting undead really fucking hard. They take a lot of work though, and require drinks between pulls. They can also be used on 4HM if you're alpha enough, apparently.
Main problem with paladin tanking is they have no taunt whatsoever so if you can't smite the everloving shit out of some zambies then you're gonna have a bad time.
They can AOE farm amazingly well though.
Funny you say that, this Naxx semi guild/pug on Northdale is lead by a pally called "theprotdream" and he's tanking Aboms in the trash packs