Here's the list that I've been able to compile off of WoWHead so far. I'll update it as I get more information, and feel free to post in the discussion thread if you find another suitable enchant for the list. Bolded items are recommended for the slot, just to help you remember.

Multislot Armor Kits (Head, Shoulder, Chest, Glove, Leg, Boot):
[Borean Armor Kit] - 12 Stamina (4 Borean Leather)
[Heavy Borean Armor Kit] - 18 Stamina (4 Heavy Borean Leather), Used most often on glove and shoulder slot

"Arcanum" Head enchant:
[Arcanum of the Stalwart Protector] - 37 Stamina and 20 Defense Rating, Requires Argent Crusade - Revered

"Inscription" Shoulder Enchant:
[Lesser Inscription of the Pinnacle] - 15 Dodge and 10 Defense Rating, Requires Sons of Hodir - Honored
[Greater Inscription of the Pinnacle] - 20 Dodge and 15 Defense Rating, Requires Sons of Hodir - Exalted
Inscribers only:
Master's Inscription of the Pinnacle - 52 Dodge and 15 Defense Rating (1 Snowfall Ink)

Chest:
Enchant Chest - Super Health - 275 Health (20 Infinite Dust, 4 Greater Cosmic Essence)
Enchant Chest - Mighty Health - 200 Health (3 Greater Cosmic Essence)
Enchant Chest - Greater Defense - 22 Defense Rating (10 Infinite Dust, 1 Eternal Earth)
Enchant Chest - Super Stats - 8 All Stats (4 Infinite Dust, 2 Lesser Cosmic Essence)
Enchant Chest - Powerful Stats - 10 All Stats (4 Dream Shard, 4 Abyss Crystal)

Cloak:
Enchant Cloak - Titanweave - 16 Defense Rating (8 Infinite Dust, 2 Dream Shard, 2 Titanium Bar)
Enchant Cloak - Major Agility - 22 Agility (8 Infinite Dust, 2 Greater Cosmic Essence, 2 Dream Shard)
Enchant Cloak - Mighty Armor - 225 Armor (15 Infinite Dust, 2 Greater Cosmic Essence)

Wrist:
Enchant Bracer - Expertise - 15 Expertise Rating (14 Infinite Dust, 3 Greater Cosmic Essence)
Enchant Bracer - Brawn - 12 Strength (6 Arcane Dust)
Enchant Bracer - Greater Stats - 6 All Stats (16 Infinite Dust, 3 Greater Cosmic Essence)
Enchant Bracer - Greater Assault - 50 Attack Power (24 Infinite Dust, 6 Greater Cosmic Essence)
Enchant Bracer - Striking - 38 Attack Power (6 Infinite Dust)
Enchant Bracer - Major Stamina - +40 Stamina (4 Greater Cosmic Essence, 1 Abyss Crystal)
Leatherworkers Only:
Fur Lining - Stamina - 90 Stamina (1 Arctic Fur)

Glove:
Enchant Gloves - Armsman - 10 Parry Rating and 2% Threat (2 Dream Shard, 8 Eternal Earth)
Enchant Gloves - Expertise - 15 Expertise Rating (12 Infinite Dust)
Enchant Gloves - Crusher - 44 Attack Power (20 Infinite Dust, 4 Greater Cosmic Essence, 1 Dream Shard)
Enchant Gloves - Major Agility - 20 Agility (4 Greater Cosmic Essence, 1 Dream Shard)
Enchant Gloves - Precision - 20 Hit Rating (4 Greater Cosmic Essence)
Enchant Gloves - Greater Assault - 35 Attack Power (6 Infinite Dust, 1 Greater Cosmic Essence)
Enchant Gloves - Major Strength - 15 Strength (12 Arcane Dust, 1 Greater Planar Essence)

Belt Socket:
[Eternal Belt Buckle] - One Prismatic Gem Socket (4 Saronite Bar, 1 Eternal Earth, 1 Eternal Water, 1 Eternal Shadow)

Legs:
[Jormungar Leg Armor] - 45 Stamina, 15 Agility (5 Heavy Borean Leather, 1 Jormungar Scale)
[Frosthide Leg Armor] - 55 Stamina, 20 Agility (2 Arctic Fur, 2 Nerubian Chitin)
Leatherworkers Only:
Jormungar Leg Reinforcements - 55 Stamina, 20 Agility (2 Jormungar Scale)

Boots:
Enchant Boots - Tuskarr's Vitality - 15 Stamina and Minor Run Speed Increase (10 Infinite Dust, 2 Greater Cosmic Essence, 2 Dream Shard)
Enchant Boots - Greater Fortitude - 22 Stamina (3 Lesser Cosmic Essence, 3 Infinite Dust)

Enchanter-only ring enchant:
Enchant Ring - Stamina - 24 Stamina (8 Infinite Dust, 1 Greater Cosmic Essence)

Weapon Options:
Enchant Weapon - Greater Potency - 50 Attack Power (2 Infinite Dust, 4 Lesser Cosmic Essence)
Enchant Weapon - Accuracy - 25 Hit and Crit rating (20 Infinite Dust, 4 Greater Cosmic Essence, 4 Dream Shard, 6 Abyss Crystal)
Enchant Weapon - Superior Potency - 65 Attack Power (10 Infinite Dust, 2 Greater Cosmic Essence, 2 Dream Shard, 4 Abyss Crystal)
[Titanium Weapon Chain] - 50% Shorter Disarm Duration and 28 Hit Rating (2 Saronite Bar, 1 Titanium Bar)
Enchant Weapon - Potency - 20 Strength (4 Large Prismatic Shard, 5 Greater Planar Essence, 20 Arcane Dust)
Enchant Weapon - Exceptional Agility - 26 Agility (4 Dream Shard, 4 Eternal Air)

Shield:
Enchant Shield - Defense - 20 Defense Rating (6 Infinite Dust, 6 Eternal Earth)
[Titanium Plating] - 40 Block Value (4 Titanium Bar, 4 Eternal Shadow)

-----------------------------

WotLK Tank Gems: Please note that this list includes some gems not currently in-game, including all epic cuts and some blue cuts.


JC-only Gems (Any Slot):
Solid Dragon's Eye - 41 Stamina
Thick Dragon's Eye - 27 Defense Rating
Bold Dragon's Eye - 27 Strength
Flashing Dragon's Eye - 27 Parry Rating
Subtle Dragon's Eye - 27 Dodge Rating
Rigid Dragon's Eye - 27 Hit Rating
Precise Dragon's Eye - 27 Expertise Rating

Meta Gems:
Austere Earthsiege Diamond - 32 Stamina and 2% Increased Armor Value from Items
Effulent Skyflare Diamond - 32 Stamina and Reduce Spell Damage Taken by 2%
Eternal Earthsiege Diamond - 21 Defense Rating and +5% Shield Block Value

Red Slot:
Bold Bloodstone - 12 Strength
Perfect Bold Bloodstone -14 Strength
Bold Scarlet Ruby - 16 Strength
Bold Cardinal Ruby - 20 Strength
Flashing Bloodstone - 12 Parry Rating
Perfect Flashing Bloodstone - 14 Parry Rating
Flashing Scarlet Ruby - 16 Parry Rating
Flashing Cardinal Ruby - 20 Parry Rating
Subtle Bloodstone - 12 Dodge Rating
Perfect Subtle Bloodstone - 14 Dodge Rating
Subtle Scarlet Ruby - 16 Dodge Rating
Subtle Cardinal Ruby - 20 Dodge Rating
Precise Bloodstone - 12 Expertise Rating
Perfect Precise Bloodstone - 14 Expertise Rating
Precise Scarlet Ruby - 16 Expertise Rating
Precise Cardinal Ruby - 20 Expertise Rating

Blue Slot:
Solid Chalcedony - 18 Stamina
Perfect Solid Chalcedony - 21 Stamina
Solid Sky Sapphire - 24 Stamina
Solid Majestic Zircon - 30 Stamina

Yellow Slot:
Thick Sun Crystal - 12 Defense Rating
Perfect Thick Sun Crystal - 14 Defense Rating
Thick Autumn's Glow - 16 Defense Rating
Thick King's Amber - 20 Defense Rating
Rigid Sun Crystal - 12 Hit Rating
Perfect Rigid Sun Crystal - 14 Hit Rating
Rigid Autumn's Glow - 16 Hit Rating
Rigid King's Amber - 20 Hit Rating

Purple Slot:
Sovereign Shadow Crystal - 6 Strength and 10 Stamina
Perfect Sovereign Shadow Crystal - 7 Strength and 11 Stamina
Sovereign Twilight Opal - 8 Strength and 12 Stamina
Sovereign Dreadstone - 10 Strength and 15 Stamina
Defender's Shadow Crystal - 6 Parry Rating and 9 Stamina
Perfect Defender's Shadow Crystal - 7 Parry Rating and 11 Stamina
Defender's Twilight Opal - 8 Parry Rating and 12 Stamina
Defender's Dreadstone - 10 Parry Rating and 15 Stamina
Guardian's Shadow Crystal - 6 Expertise Rating and 9 Stamina
Perfect Guardian's Shadow Crystal - 7 Expertise Rating and 11 Stamina
Guardian's Twilight Opal - 8 Expertise Rating and 12 Stamina
Guardian's Dreadstone - 10 Expertise Rating and 15 Stamina
Regal Shadow Crystal - 6 Dodge Rating and 9 Stamina
Perfect Regal Shadow Crystal - 7 Dodge Rating and 11 Stamina
Regal Twilight Opal - 8 Dodge Rating and 12 Stamina
Regal Dreadstone - 10 Dodge Rating and 15 Stamina

Green Slot:
Enduring Dark Jade - 6 Defense Rating and 9 Stamina
Perfect Enduring Dark Jade - 7 Defense Rating and 11 Stamina
Enduring Forest Emerald - 8 Defense Rating and 12 Stamina
Enduring Eye of Zul - 10 Defense Rating and 15 Stamina
Vivid Dark Jade - 6 Hit Rating and 9 Stamina
Perfect Vivid Dark Jade - 7 Hit Rating and 11 Stamina
Vivid Forest Emerald - 8 Hit Rating and 12 Stamina
Vivid Eye of Zul - 10 Hit Rating and 15 Stamina

Orange Slot:
Champion's Huge Citrine - 6 Strength and 6 Defense Rating
Perfect Champion's Huge Citrine - 7 Strength and 7 Defense Rating
Champion's Monarch Topaz - 8 Strength and 8 Defense Rating
Champion's Flawless Ametrine - 10 Strength and 10 Defense Rating
Etched Huge Citrine - 6 Strength and 6 Hit Rating
Perfect Etched Huge Citrine - 7 Strength and 7 Hit Rating
Etched Monarch Topaz - 8 Strength and 8 Hit Rating
Etched Flawless Ametrine - 10 Strength and 10 Hit Rating
Glimmering Huge Citrine - 6 Parry Rating and 6 Defense Rating
Perfect Glimmering Huge Citrine - 7 Parry Rating and 7 Defense Rating
Glimmering Monarch Topaz - 8 Parry Rating and 8 Defense Rating
Glimmering Flawless Ametrine - 10 Parry Rating and 10 Defense Rating
Resolute Huge Citrine - 6 Expertise Rating and 6 Defense Rating
Perfect Resolute Huge Citrine - 7 Expertise Rating and 7 Defense Rating
Resolute Monarch Topaz - 8 Expertise Rating and 8 Defense Rating
Resolute Flawless Ametrine - 10 Expertise Rating and 10 Defense Rating
Stalwart Huge Citrine - 6 Dodge Rating and 6 Defense Rating
Perfect Stalwart Huge Citrine - 7 Dodge Rating and 7 Defense Rating
Stalwart Monarch Topaz - 8 Dodge Rating and 8 Defense Rating
Stalwart Flawless Ametrine - 10 Dodge Rating and 10 Defense Rating