WoWCenter.pl
wikass zabił Mythrax the Unraveler (Normal Uldir) po raz 2.     
kuturin zdobył 7th Legionnaire's Cuffs.     
Nikandra spełnił kryterium Loot 200,000 gold osiągnięcia Got My Mind On My Money.     
Tooly zdobył Fairweather Helm.     
Muattin zdobył osiągnięcie The Dirty Five.     
Yoozku zdobył Parrotfeather Cloak.     
Mlody89 zdobył Royal Apothecary Drape.     
Weakness zabił Dazar, The First King (Mythic King's Rest) po raz 6.     
liq spełnił kryterium osiągnięcia Saving for a Rainy Day.     
Osiol spełnił kryterium osiągnięcia Saving for a Rainy Day.     
Wuntu zabił Zek'voz, Herald of N'zoth (Heroic Uldir) po raz 1.     
Olsa zabił Vectis (Heroic Uldir) po raz 6.     
Sarenus spełnił kryterium osiągnięcia Saving for a Rainy Day.     
kajtasus zdobył osiągnięcie Come Sail Away.     
ossir spełnił kryterium osiągnięcia Saving for a Rainy Day.     
mcpablo spełnił kryterium Alliance players slain. osiągnięcia Frontline Slayer.     
Emmm zabił Taloc (Heroic Uldir) po raz 17.     
AsaGorth spełnił kryterium Big-Mouth Clam osiągnięcia The Oceanographer.     

Amalzyth

There's currently a major bug somewhere (I personally do not know where) that's granting players a +500% haste buff that's allowing groups to complete all 8 challenge modes in insanely ridiculous times, regardless of gear or talent specializations.

Just look at these times (armory is buggy):
Shadowmoon Burial Grounds: 14:02 -- Three tanks, a warlock, and ret paladin. That's 3 minutes and 30 seconds ahead of the timer nearly 20 points below the intended item level for challenge modes.

Here's a few characters:
http://us.battle.net/wow/en/character/blackrock/Kami/advanced
http://us.battle.net/wow/en/character/kelthuzad/Anpylol/advanced (618 item level)
http://us.battle.net/wow/en/character/kelthuzad/%C3%82meyuri/challenge (620 item level)

There are plenty more examples for both times and characters, but I could spend all night finding and linking them.

And if you're questing the bug -- here's a screenshot of the attributes page:
http://i.imgur.com/QiGKxkq.png

As you can see... +548% haste.

I assume something will be done about this? It takes a lot of fun out of the game when you can simply use an exploit and take what's supposed to be a challenge (no pun intended) and make it easier than a normal mode.