My overlords have allocated me one VM and externally-routable IP for use on a certain project, and I've since discovered that the software that runs on this is essentially a singleton (no more than 1 instance running) and darn it, I have to have about 8 of them. So I could go back to the overlords and say "Hey, I need 2 more VMs maybe 3" but if I ask for 8, my ears will hurt for a week.
So maybe I can set up a VM running within a VM. Sort of like "Zones" within BSD. I know enough about XEN to know this might be possible. But I don't know for sure.