I don't know about more recent versions, but under 1.4.x a 3/50, even
unexpanded, could do useful work with a stripped kernel. Interactive use
would be agonizing, but they make decent authoritative DNS servers running
BIND 9.1.2. Since they're authoritative-only, the named process has a fixed
size and just sits in memory doing its thing. They handle 10,000+ lookups a
day while being 99% idle.

   FYI, you *don't* want to run a 3/50 with swap on NFS, disk is an order
of magnitude faster. I had one, expanded to 8M, which I was running diskless
under 1.4.x -- it took about three solid minutes of network activity to
complete a "ps -aux".

   --James B.