Transcendent Lightling

Finally finished my transmog set built around Robes of the Exalted.

Aurora of Transcendence Dropped in Blackwing Lair.  Priest only.
Lightning Infused Mantle Quest reward from Halls of Lightning.  Don't despair if you did this quest when WOTLK first came out and then vendored these shoulders.  The WOTLK dungeon quests have been reset and the quest giver is now inside the entrance of the dungeon.
Robes of the Exalted Drops from Lord Aurius Rivendare in StratholmeRuned Spell-Cuffs Bought for Justice Points in ShattrathFrostweave Gloves Crafted by tailors
Hammer of the Astral Plane Drops from Kel'thuzad in Naxx 10
Igniter Rod Drops from Ignis in Ulduar 10
Dawnspire Cord Drops in Sunken Temple

Corrupted Mooncloth

Vengeful Gladiator's Mooncloth Hood Priest-only PvP reward.
Merciless Gladiator's Mooncloth Mantle Priest-only PvP reward.  The token to buy it drops from Void Weaver in The Eye.  ** Update 11/22/2013:  Not sure when this changed, but you can now buy this from Kezzik the Striker in Area 52 in Netherstorm for 750 Honor.  **
Raiments of the Corrupted Drops in Ulduar 10
Binding of the Dragon Matriarch Drops in Ulduar 10
Pulsar Gloves Drops in Ulduar 10
Royal Boots Green BOE
Tower of the Mouldering Corpse Drops in the Forge of Souls
Deathchill Cloak Made by Tailors.  There are a few other cloaks with the same appearance.

Details here.

Sun-Infused Sin'dorei

Circlet of Prophecy Priest Tier 1.  There are lookalikes--check Wowhead.
Flarecore Mantle Made by tailors.  Requires Thorium Brotherhood rep to buy the pattern.
Scarlet Sin'dorei Robes Drops in heroic Magister's Terrace.
Girdle of Ruination Made by tailors.  Pattern is a world drop.
Imperial Red Gloves Green BOE
Imperial Red Boots Green BOE
Perdition's Blade Drops in Molten Core.
Flametongue Seal Bought for Justice Points in Shattrath.

Alternate versions

Whitemend Hood Made by tailors.
Primal Mooncloth Shoulders Made by tailors.
Girdle of Prophecy Priest Tier 1
Sun-Infused Focus Staff Drops in Magister's Terrace.  The green BOE Frenzied Staff is another Blood Elf style staff.

Red Linen Sash Alliance only quest reward in Elwynn Forest.
Mantle of the Corrupted Drops in Naxx 25.
Lok'amir il Romathis Drops in Blackwing Lair.

All details here.

Icy Mooncloth

Here's a set based around the Mooncloth Robes for a Frost Mage or healy Priest.

Royal Headband Green BOE
Regal Mantle Green BOE
Mooncloth Robe Made by tailors
Ebonweave Gloves Made by tailors.  They are long enough that most bracers shouldn't show.
Mindfire Waistband Drops in the Blood Furnace
Staff of the Unknown Road Quest reward from Zul'Farrak
Regal Boots Green BOE

Alternate version

Underworld Mantle Drops in Ulduar 10 normal
Grand Magister's Staff of Torrents Drops in Sunwell Plateau

Alternate Shoulders

Khadgar's Shoulderpads of Triumph Alliance Mage Tier 9

Merciless Gladiator's Mooncloth Mantle Priest-only PvP reward.  The token to buy this drops from Void Reaver in the Eye.

Sanctified Crimson Acolyte Mantle Priest Tier 10

All details here.

Primal Mooncloth Dragon Slayer

Combines pieces from the Primal Mooncloth set and a low-level Alliance quest reward.

Whitemend Hood Crafted by tailors
Primal Mooncloth Shoulders Crafted by tailors
Robe of the Dragon Slayer Quest reward from Alliance only quest on Bloodmyst Isle
Primal Mooncloth Belt Crafted by tailors
Sterile Flesh-Handling Gloves Requires Knights of the Ebon Blade reputation to purchase
Ethereal Boots of the Skystrider Drops in normal mode Mana Tombs
Gavel of Pure Light Requires Sha'tar reputation to purchase.  There are several other maces with the same appearance--check the Wowhead link.
Swamplight Lantern Drops in heroic Slave Pens


Details here

Update 6/23/12:

Got tired of farming heroic Slave Pens for the Swamplight Lantern, got even more tired of farming Arcatraz for a slightly different color of the same model, and I didn't feel like spending my Justice Points on Hermit's Lamp.  I lucked out and found Dreamseeker Dandelion for sale at the Auction House, so I went with that for my offhand.

Update 8/17/12:

Alternate weapon:  Redemption.  Drops in what we used to call Live Strat.

Exalted Lightning

Based around Robes of the Exalted from Stratholme and Lightning Infused Mantle.

Aurora of Transcendence Dropped in Blackwing Lair
Lightning Infused Mantle Quest reward from Halls of Lightning.  Don't despair if you did this quest and  when WOTLK first came out and then vendored these shoulders.  The WOTLK dungeon quests have been reset and the quest giver is now inside the entrance of the dungeon.
Robes of the Exalted Drops from Lord Aurius Rivendare in Stratholme
Runed Spell-Cuffs Bought for Justice Points in Shattrath
Frostweave Gloves Crafted by tailors
Nethershard Girdle Dropped by Moroes in Karazhan
Slippers of Serenity Dropped by Exarch Maladaar in Auchenai Crypts
War Mace of Unrequited Love Dropped by Keristrasza in heroic The Nexus
Swamplight Lantern Dropped by Quagmirran in heroic Slave Pens

Details here

Alternate version #1.  You'll have to find some pants that don't show too much.

Robes of the Guardian Saint Drop from Temple of Ahn'Quiraj
Dawnspire Cord Drops in the Sunken Temple

Details here

Alternate version #2, using Replica Virtuous Crown as well as the replicas of the bracers, gloves, and belt from the Vestments of the Virtuous set.

Details here

Versions by other people here.

Ruthless Pigment

Based on the Kalu'ak Pigment-Stained Robes.  The helmet is priest-only.

Details here

Ruthless Gladiator's Mooncloth Helm Priest-only PVP
Fel-Tinged Mantle Drops from Vexallus in Magister's Terrace
Pigment-Stained Robes Kalu'ak rep gear
Nethershard Girdle Drops from Moroes in Karazkan
Moonshroud Gloves Crafted by tailors
Ethereal Boots of the Skystrider Drops from Nexus-Prince Shaffar in the Mana Tombs