I regularly enjoyed besieged.
All you had to do was turn the chat to "You + Your Party"
And it seemed to limit the number of mobs people on screen, prioitising my party/alliance and the mobs we fought.
I'll admit, there were a couple of times when my xbox would crash out of besieged, alot of xbox users would.
And Ninja-WTF-just-ate-me deaths.