I have a bunch of things that I've written for myself, though I don't spend as much time doing so these days.
I have a few re-interpretations of web services I use: ggg is a git resository server, trobble a scrobble catcher, and ihkh a minimalist flickr viewer, based on another that is long dead.
I also started writing papiermache, an instapaper-style service, but stopped using my kindle to read articles so never fleshed it out enough to be useful.
After Google Reader closed down I wanted to write my own feed reader. At first it was going to be an inbox style reader but then I became interested in the river-of-news style after seeing river2, so wrote riviera to do so (also see rivelin, a river.js reader, and riviera-admin, an admin panel for riviera).
Later I saw fraidyc.at which seemed a better model for how I wanted to read most feeds, so I totally copied the idea into arboretum.
For a time I was trying to “indiewebify” my homepage. Along the way I wrote relme-auth, a service that provides the ability to sign-in with your website, which along with the indieauth package allowed me to provide a consistent way to authenticate on my own projects for others, not just myself (prior to this I was using another service I had written, uberich, which was inspired by Mozilla's Persona).
I also wrote a micropub blog, tally-ho, which tried to tick off a bunch of the indieweb specs, along with integrations to twitter, github, and flickr.
While creating these web apps I've written a few useful libraries that allow me to continue creating them the way I want:
I have a Raspberry Pi with Music Player Daemon on to play my music collection, that I no longer use…. But when I did, I wrote a few tools for it: ashuffler, evmpd, mpd-scrobbler, and mpd-sound-menu.