I've recently come across the Lobsters Blog Carnival, and though I'm not yet a member of Lobsters, I can certainly answer to their theme: "What have you made for yourself?"
Heck, I've got a couple of things in that category...
One of them comes from my not wanting to pay for the privilege of publishing Obsidian vaults to HTML sites, which is why I created dragonglass. (Named, of course, because obsidian is called "dragonglass" in Game of Thrones and A Song of Ice and Fire.). It converts an Obsidian vault's Markdown pages to HTML, and copies everything else in the vault over verbatim. I used the Python-Markdown parser for the heavy lifting, but I had to extend the hell out of it to support Obsidian-flavored Markdown. It even has its own little extension mechanism, which adds breadcrumb-style navigation to pages, controlled by certain metadata values.
Then there's distance-calc, which I used because I was thinking of moving to an apartment complex closer to the VMware Carbon Black office in Boulder. It uses Google Maps APIs to geocode individual addresses, then does some trig to calculate the crow-flies distance from each of those addresses to the office, and even uses Google Maps to estimate the drive time. I ran this on a number of apartment complexes...but never used the results, as 2020 happened and we all started working from home, so moving was no longer necessary.
And, of course, I've supported my Minecraft addiction by creating my own modpacks, the two most recent of which are Erbosoft Vista and Erbosoft Sierra. (And yes, I took the names from Windows Vista and macOS Sierra.) They were built for use with the Technic Platform, and allowed me to set up a private server with those modpacks for myself, my then-roommate, and a few of our other friends. The versions of Minecraft they use are way out of date, though, so, recently, I've just been playing the most recent version in vanilla mode.
That doesn't even count Venice...or Venice's forthcoming follow-on, still under wraps for now...