UPDATE: No loot, HP resets, not sure about rep.
THIS STILL WORK AFTER THE HOTFIX.
I'm doing this as a hunter and I can currently think of any class beside mages and NE's with shadowmeld who can do this, HOWEVER.
What we're killing is:
http://www.wowhead.com/npc=53631 120k elite spiders which DOES NOT GET BACK FULL HP WHEN YOU RESET COMBAT.
It's pretty simple not much of a guide to write, Kill or damage the mob, reset somehow then repeat once cd back up.
No loot table is shown on wowhead for theese guys but in my own experience they can drop 1g-5g and greens, so i'm expecting they will drop epics if I get some luck too. I guess I should mention it's 6 rep per spider aswell.
Also you can shoot at the two cinderweb SPINNERS and loot em after the Big guy kills em, after a instance reset.
And they can be skinned. Will add pictures if requested.
EDIT : I forgot to add on top of theese spiders there's an elite called Molten Lord which has 3874k hp and his HP DOES in fact reset, don't let him hit you, he hits my hunter on avg for 60k. 160k on crits.
EDITEDIT: Might be common sense but if you mess up and kill it ontop of the elite you can misdirect the big guy to your pet then feign death, or if it's slightly out of range of the boss you can loot while in camo, just a tip.
EDITEDITEDIT: In conjuction with WoWExt (Look under Programs and bots), you can go to other packs of spiders which where there is no elite also you can as a hutner with trap kite the spiders unlimited spamming Multi-Shot, easy profit. : )