In ~2003, I replaced my desktop that had been Intel-based with a Duron 800MHz system, only I didn't have enough budget to get it the RAM it required (new/different slot iirc), so I only had the 128MB it came with (whereas my old machine had 768MB cobbled together from like six dimms).

I figured that one hop over 100Mbit Ethernet to remote memory was going to be faster then swapping to spinning rust (remember this was before consumer SSDs, and onions on our belts), so I made a ramdisk on the old machine and mounted it over the network with the nbd (network block device) kernel driver, ran swapon on the nbd and boom, extra "512MB" of RAM.

It worked amazingly well, and (knock on wood) none of my roommates ever tripped over the Ethernet cables.