I dont say this is a Exploit, but imagine this:
(only works on PVE, not PVP)
You have a char with AOE eg. Mage. Lets say you are Alliance, then make a char on horde side, find a HUGE Horde Guild +80 players lvl 60. And now comes the hard part. You have to convince a player in the guild (A player with High Rank in the guild) to let YOU kill them, and many of them ofc, like 50-xxx horde. Maybe pay them in gold through the common AH. Gather the Horde some place, they take all items off so no repairofc. and u just kill them over and over again..
1 lvl 60 horde = about 300 honor
80horde*250honor=24000 honor
kill them 4 times=96000 Honor.
Or maybe it is not worth the time. It is up to you.