Details are just another computer user, not a "developer", writing their own utilties. Continually editing, updating to suit personal needs. No prerequisites except flex and C89 compiler. Generally, static binaries under 50k.

A search on one of the search engines that indexes HN may provide some pointers. Something like site:ycombinator.com plus [name of filter].

Not sure about "interesting" but these are portable across OS, low resource requirements. Faster than sed. Boring stuff that works for me year after year.