As far as “tooting my own horn” goes, I wrote a readable emulator for the MOS 6502 in Common Lisp. My original goals included writing a full NES emulator on top of it, then tools for the reverse engineering, observation, and runtime modification of Nintendo ROMs. Probably including a compiler for a lisp-like language targeting the emulator.
I got a new job I find much more challenging though, so this isn’t likely to happen ‘til I retire. :P For a decent NES emulator, sprocketnes is actually quite clear even without knowing Rust.
Interesting projects I’ve been meaning to read include the following: