Here are some of the sets I was able to find on Allakhazam:
Defias Leather - 5 pieces of leather armor that drop from various enemies and bosses in The Deadmines. Level range from 13 to 19. Enhances Strength (15), Agility (9), and Stamina (14). Looks to be intended for rogues (there is a boost to Dagger skill if you complete the set), but also probably good for hunters.
Chain of the Scarlet Crusade - A 6-piece mail set ranging from Lv30 to Lv38, dropping from various enemies in the Scarlet Monestary. Mostly boosts to Strength & Stamina (with a little bit Agility), completing the set offers more offense-oriented bonuses.
Vestments of the Devout - Eight pieces, all rare, level range from 52 to 58. Some drop in Stratholme, others in Blackrock Spire, and I couldn't find any location info on a few. This cloth set is generally helpful to spellcasters (Intellect +134, Spirit +104, Stamina +65, Agility +12), and the completion bonuses make me think it's intended for priests.
I can't find much on the
Devotion set as it doesn't appear to be in the Alla database. Thottbot says that it's eight pieces (of which there are records for six), all rare, from levels 52 to 57. As with the Devout set, boosts to Intellect, Spirit, and Stamina. Once pieces drops in Stratholme, another in Scholomance, nothing known about the completion bonuses.
There are only two pieces of
Ironfeather Armor, but it looks decent. Levels 49 and 53, leather gear. Enhances Intellect and Spirit, and completing the set gives you an increased resistance to silence. This one is interesting in that it's player-crafted, no information on how to get the recipe.
Stormshroud Armor is also player-crafted leather (recipes drop from Azshara) for levels 50 through 54. This looks like melee-oriented gear, as it improves critical strike and dodge chances. Completing the set gives you a lousy 15-25 Lightning "5% proc on hit" effect. Meh.
More love for rogues in
Shadowcraft Armor. This is leather armor with a level range of 52 through 5 and boosts to Agility (136), Stamina (84), Spirit (36), and Strength (43). Completion bonuses seem very obviously aimed at rogues (Dagger skill, critical hit %, dodge %, hit %, offhand hit %). Drops from Blackrock Spire, Scholomance, and Stratholme.
I'm thinking that
Wildheart Rainment is for druids and hunters. Strength +26, Intellect +122, Spirit +110, Stamina +65, Agility +12. The whole set enhances Arcane, Nature, and healing spells, plus some minor boosts to Strength & Stamina. This should sound familiar: levels 52 through 58, drops in Blackrock Spire, Scholomance, and Stratholme.
Devilsaur Armor is another small, crafted leather set. It boosts Strength, Stamina, and attack power. Nothing is known about completion bonuses, and the recipes drop in Un'Goro Crater.
Cadaverous Garb is a leather set from Scholomance. Because of the Strength, Stamina, and Agility boosts I assume it's melee oriented (not sure which melee classes wear leather at 50+). It's all level 56 equipment, and drops from undead in Scholomance.
I can't find much about the
Beaststalker gear, save that it's mail in the upper 50s. With the name one would assume it's for hunters.
The Elements is also a mail set that hunters seem suited for, along with druids & shamans. Boosts to five abilities, though Intellect and Spirit get the biggest bumps. Completion gives better Frost, Fire, and Nature Resistance, plus a enhancement to Nature damage and healing spells. This one is level 52 to 58 and all known drops are in Blackrock Spire.
The
Battlegear of Valor set looks very spiffy. It's designed for tanking, with a large Stamina boost (+131) and good enhancements to Strength, Agility, and Spirit. Completion gives more Armor, Attack Power, plus a tiny (2 Arcane) thorn effect and 5hp/sec regen. Usual level range (52 to 58) and drop locations (Scholomance, Stratholme, Blackrock Spire).
Deathbone Guardian is another plate set for tanking. It's mostly like the Valor set, except the completion bonuses (Defense, Armor, Reistance, parry %) are purely defensive. You can get this five-piece set in Scholomance.
Lightforge Armor is probably for high-level (52 to 58) paladins. An eight-piece plate set which boosts to Strength, Stamina, and Spirit as expected. The whole set will enhance your attack power against undead & demons, boost your healing spells, and give you a 1% chance of receiving a 500 damage shield every you get hit. Aside from the usual drop spots, one piece is from the final boss in Blackrock Depths.
Wow. Quite a lot. I had no idea the list would be so long when I started compiling it. While there is a handful for low-level folks (Defias Leather, Scarlet Mail), mostly it's for people who have reached the high-level endgame.