Prototypes, models and little tools. Most of them are unfinished, which is part of the fun.
A flight-feel sandbox for a small spaceship game. Six degrees of freedom, inertia you can feel, and a lot of tuning knobs.
Rebuilding a room from a phone scan before moving out, so it can be kept after the keys are returned.
A home-screen web app that shows bus arrivals at the stops I actually use, and nothing else.
A tiny spaced-review program for vocabulary, picking the words I am about to forget.