spiral
General purpose editing of lines in a terminal. Available as a Zig library, as well as a separate executable. Intended usage is command-line applications working in a REPL fashion, where every line could require rich editing.
FCDL
A Linux kernel module written in C. Creates a special character device that, when being read from, outputs every created or deleted file on the entire system. It does so by intercepting system calls. My first Linux Kernel module ever developed. Not very practical for use, because Inotify exists.