Everyone know that blizzard during vanilla didnt get about class balance.
Thats why they buffed many classes/item sets during TBC, making all classes and all specs more usefull both in PvP/PvE.
I'm not talking about item sets for Tanks/DPS/healers, but there is few options that can raise up class balance:
Paladin: Crusader Strike. Paladins are pretty useless in anything except healing, Reck PvP is awful. And instant strike can buff paladins, making em more usefull both in PvP/PvE. As you know, blizzard got their mistake and re-added this ability with TBC talents. You can add it at 40 lvl trainer.
Warrior: Warriors are highly bad in PvP if soloing because of vuln to slowing/movement impairing effects.
There is few suggestions:
1. Some kind of "Second Wind" passive ability (health+rage regen while under effects), or maybe some kind of -dmg taken while under slow.
2. Good old Spell reflect
3. Buffing Enrage talent to 40% from 25%, as it was before.
Hunter: Aimed shot cast speed should be buffed up to 1,5-2,0 sec. This will allow hunters do more DPS in PvE, and slighly buff em in PvP.
Druid:
Moonkin and Feral +3% crit should affect whole raid instead of group.
Also Omen of Clarity should proc of any dmg including spells.
Even blizzard got this is fair way, when they introduced this things in to game.