Under construction - listing of world bosses, rare mobs and all interesting mobs which is good to kill.
Mind that rare spawns in Outland always drop blue items. And some rares in Outland are elite - something not really common in pre-TBC game.
Doomwalker - Fel Reaver - World Boss
Doomwalker walks around entrances to The Dark Temple
Currently known abilities:
Earthquake - 2k Damage every 2 seconds (Total 8k Damage)
If you are killed by Doomwalker you gain the Debuff "Mark of Death. This debuff (similar to the Dragons of Nightmare bosses), means that you can only attempt this boss once every 15 minutes.
Kraator - 68 Elite Demon - Rare
Drops all different pieces of "Abyssal" armor in all forms (plate, cloth, leather, mail) and with some random enchants.
Has 95,000HP and summons Infernals irregularly. He conflagrates like Razorgore the Untamed and General Drakkisath. Fire shield for ~500 Fire damages.
Shadowmoon Valley - Ambassador Jerrikar - 69 Demon - Rare
Ruins of Baar'ri - drops "Illidari" pieces of armor (all kind) with different stats.
Speaker Mar'grom - 68 Humanoid - Rare
Spawns in various oggre camps, drops "Nethersteel" hands with some random stats.
Doomsayer Jurim - 64 Humanoid - Rare
Spawns somewhere in forest part of Terokkar zone. Drops "Grim" boots with some random stats.
Spawns in bird-people camps, drops "Feathered" Waist with random stats.
Crippler - 65 Undead - Rare
Spawns somewhere in Bone Wastes (area around Auchindoun), drops Dragonbone Ring which is a ring with random stats.
Bog Lurker - 63 Elemental - Rare
"Bog" armor with different stats, various spawn points.
Coilfang Emissary - 64 Humanoid - Rare
Spawns at naga places, drops various "Nagahide" and "Nagascale" legs with random stats.
Goretooth - 65 Beast - Rare
Drops "Crocolisk Scale" and "Crocolisk Hide" bracers with random stats.
Bro'Gaz the Clanless - 66 Humanoid - Rare
Various spawn points, probably main drop is Gronn-Blessed Warbeads - Neckplace with random stats at drop.
Chief Engineer Lorthander - 69 Humanoid - Rare
Spawns at mana forges - probably drops only Illidari Cloak which is a cape (back) with random stats.
Ever-Core the Punisher - 68 Elemental - Rare
Various spawn points. Drops Arcane Loop, ring with some random stats.
Nuramoc - 70 Elite Beast - Rare
Flying 2headed monster attacks players on flying mounts, drops Chimeara(scale/hide/etc) leggs.
Vorakem Doomspeaker - 62 Demon - Rare
Spawns in Invasion camps and drops "Legion" head with some random statst.
Mekthorg the Wild - 61 Humanoid - Rare
Spawns around the base of Hellfire Citadel, drops "Demon" chests with random stats.
Doom Lord Kazzak - Demon - World Boss
Kazzak was well known to reside in Blasted Lands. With TBC he was relocated to HFP and renamed to "Doom Lord Kazzak" - he is atop of Throne of Kil'Jaeden. Blasted Lands location of Kazzak is populated with Highlord Kruul - one of Kazzak's minions.
Some of Doom Lord Kazzak's abilities appear to be the same as those when he resided in Azeroth, just with higher damage. There are almost certainly other abilities as yet undocumented.
Shadowbolt Volley - Shoots out an insanely long range volley of Shadowbolts that damage anything it can target in distance for a largish amount of damage (was around 1000 pre-Burning Crusade). The volley totally ignores all line of sight issues: it cannot be dodged.
Twisted Reflection - Casts a magical debuff (on a random player in range other than the player with aggro) that. heals Lord Kazzak for a very large proportion of his health (was 25,000 pre-Burning Crusade) each time he deals damage to the player with this debuff. This combined with the Shadowbolt Volley can ruin the attempt.
Mark of Kazzak is unconfirmed but likely as well, pre-Burning Crusade version:
Casts a non-curable debuff (on a random player in range with mana) that drains the target's mana for 450 per second and explodes for 4,000 AoE damage when there is no more mana to drain. A living bomb.
Cleave is unconfirmed but likely as well, pre-Burning Crusade version:
Attacks a number of melee range players around him with a cleaving strike that deals 1000-2000 damage to each. Since a 'blind spot' has not been found, Cleave might be capped to a certain number of players affected.
Thunderclap is unconfirmed but likely as well, pre-Burning Crusade version:
A PBAoE spell, hardly dealing any damage, but slowing movement speed. Some have reported 200 damage, some say it doesn't deal damage at all. Doesn't seem to affect attacking speed either.
Void Bolt - A strong bolt he may cast only on the player with aggro, deals 3000 shadow damage (or more!). A mage was hit for roughly 5000 twice.
Capture Soul - When a player, pet or totem gets killed, Lord Kazzak casts this spell to instantly regenerate a large amount of health (was 70,000 pre-Burning Crusade.