Network Block Device / nbd
The kernel module for nbd is already available in Solus but the software, which is required in order to use it, is missing from the repo
What is it: With this compiled into your kernel, Linux can use a remote server as one of its block devices. Every time the client computer wants to read /dev/nbd0, it will send a request to the server via TCP, which will reply with the data requested. This can be used for stations with low disk space (or even diskless - if you use an initrd) to borrow disk space from other computers. Unlike NFS, it is possible to put any file system on it.
My use case: I like to tinker with old hardware. This is useful to mount legacy devices on modern computers with up-to-date kernel drivers.
Admittedly, I don't expect a lot of people have a need for this, but it would be nice to have. :)