“Trusting Trust” is one of my favorites.

I bootstrapped Go 1.14 for FreeBSD 8, with a couple of patches for older syscalls, but I didn't go as far as bootstrapping GCC. I wanted to build a tool that would automatically bootstrap Go (gc and gccgo), but I lost momentum before finishing.

More recently, I bootstrapped Rebol 3, which is a self-hosted compiler, but I couldn't get to the bottom turtle since old versions were closed-source.