I know in a way we have done this with some small events that rarebit has done, where spawns of enemies are made and they attack.
How about at unscheduled times , randomly groups of fighters spawn and attack, and a message is broadcast that such an attack is taking place.
Why would people want to fight?
If you have it that these random attack NPC's have more info and the possiblity of better items, it then essentially becomes a mini event itself.
Now we could use those attackers from crits or simply high lvl of a particular gang.
[System] Attacks in progress by exiles, <<some kind of hint to which type >>, the gang used would be in that area.
Then people could search around to find these higher lvl exile gang mobs which give better rewards, and obviously those who find it first and call in help benefit more.
