vygr/ChrysaLisp: Parallel OS, with GUI, Terminal, OO Assembler, Class libraries, C-Script compiler, Lisp interpreter and more...
A Lisp-based operating system that can be run on many machines, and under the "main" OS.
Install Linux on a MacBook Air
Explainer on how to get Linux up and running on a MacBook Air. I’ve got an old “legacy” Air and this could be a good use for it.
Mezzano
Operating system written in Common Lisp. Even runs DooM and Quake!