Tons of EQ exploits but a couple that were a bit more unique/possibly not known about:
This next one was a lot more known, since a lot of people were using it when it was a thing. I also did this on The Sleeper so it's circa 2007, however I have no idea how long this exploit was in the game. I used it for months on The Sleeper and don't remember it every getting fixed while I was playing. This exploit was pet pulling, and the way it worked was this: when an NPC is aggroed it generally keeps firing off a "shout for help" ability which is what causes passive mobs to aggro on you. However, if a pet conned green TO the mob it attacked (and got initial aggro), the NPC would never shout for help at all while that pet was still alive.
The Sleeper event in Sleeper's Tomb was also really broken back then. Our guild did the standard thing of leaving 1 warder up so we didn't trigger the event and nerf the zone. When we were done with Sleeper's Tomb we killed all 4 warders to experience the event, Kerafyrm spawned and murdered us all as expected. However, a friend of mine ventured back into the zone about a month later and discovered that the warders were still there. From this point on a group of us would secretly farm the warders and sell shit like gnome illusion masks and scepters of destruction for ludicrous amounts of plat. We eventually got so rich there was no point in farming the stuff anymore.