Back in ~2003 I had bought a new motherboard + cpu (a Duron 800MHz IIRC) but as a poor college kid, only had enough money left over for 128MB of RAM.. but the system I was replacing had ~768MB. I made a ~640MB ramdisk on the old system and mounted it on the new system as a network block device, and the result was much, much faster than local swap (this was before consumer SSDs though).

[0] "nbd" / https://en.wikipedia.org/wiki/Network_block_device ; this driver is of course still in the kernel; you could do this today with an anemic raspberry pi if you wanted

Now I'm imagining a rack of raspis acting as one giant ram swap drive over nbd. This could work for a given value of "work". cost of pi vs stick of ram. A kv storage as well perhaps.

Then again, whats a TB worth on just one xeon server? Probably cheaper... or not?

Have you seen the cost of Pis lately :)

Didn't say much about availability either :P

Not really. The issue is with throttling.