I don't know*
if you know but the Microserver is capable of running ESXi 5.1 with 2 or 3 VMs, (given a bit more RAM) - quite a few reports of people doing it.
If you want to have a play with it, you could remove your existing HDDs and plug in a temp storage HDD, plug a flash drive into the internal USB connector and install ESXi on it.
ESXi 5.1 for it can be downloaded from here
You could conceivably run your FreeNAS within a VM on it as well as another 1 or 2 VMs. Won't be suitable for playing games but it might be for some low powered or long time frame work.
Just an idea.* Does this fulfill the "Tell me something you don't know..." ?