My custom keyboard layout Conkey [0] is surely my most prominent one — I use it constantly (including for typing this very comment). I hate the way the base US layout tends to get distorted in other keyboard layouts with good support for non-ASCII characters, so Conkey had the explicit goal of retaining that basic unshifted layout. I’ve also ended up porting Conkey to Mac and Linux — and given that I’m slowly switching from Windows to Linux, at least the Linux ports have ‘scratched my own itch’ too, which is nice.

Also, I made a utility to archive the full text of every website I view and store it in a SQLite database for searching. It’s proven pretty useful when I want to find something I saw a while ago and then forgot. (I haven’t attempted to open-source it, though — it consists of three entirely separate components, two of which were a pain to set up. I must try to get it into a more usable state one of these days.)

What else… my sound change applier [1], perhaps? Not that I use it very much, because I only need it on those occasions when I want to do some conlanging, which I haven’t had much time for recently. Actually, sound change appliers strike me as being very much a ‘scratch own itch’ type of project in general… sometimes it feels like every conlanger has written their own, and no two can agree on a nice design. Everyone just has their own unique preferred way of doing things.

[0] https://github.com/bradrn/Conkey

[1] https://github.com/bradrn/brassica