This is a wiki for uncommon services that can be hosted on a server. I'd interested in anything which is less common whether it's due to obsolence (eg: gopher protocol), or newness (eg: Podcast Producer service), or just limited user base.
although i'm unsure if any of 'big three server oses' supports them I'll list some of of more uncommon protocols:
you can find more of them here.
since you did not mentioned which OSI level protocol you are interested in i'll start with lower parts of the stack - i wished those ware gone away long time ago but yet they still lurk around:
and more of telecoms archeology.
and maybe ethernet - although +30 years old it seems to be still in use ;-]
VINES was an early network protocol.
We also used to transfer files using KERMIT over serial lines.
Another specialist serial protocol used in semiconductor manufacturing was SECS and SECS II (pronounced "sex", a vendor had buttons made up for a trade show that said "talk SECS to me")
There's always the LANtastic 8.0 client, which runs under Windows XP and earlier that made use of some unusual proprietary extensions to NetBIOS, and a custom EtherType to support LANtastic-specific functionality.
You can also use DECnet, LAT and the DEC DNA Routing Protocol under recent Linux distributions, if you modprobe the decnet kernel module, and install the DECnet-specific utilities (packaged as dnprogs, at least in Fedora).
Of course, AppleTalk still works after all these years, and a lot of print servers still support it. There's an implementation in the Linux kernel, which can be used with NetATalk; Mac OS X still supports it to an extent; and there are also implementations of clients and/or servers in various versions of Windows.
There are a few others, too although I can't remember right now.