A music composition web app in rails + angularjs which focuses on extremely fast composition via typing. Under the hood it uses MusicDNA (below) to generate music. This one took 3 years.
I personally use it still when writing new pieces. I'm the only one on the planet Earth, unless I make it available (no one's askin').
Lesson learned: music software is impossible to finish. There's always another integration or feature needed.
This is a DSL (domain-specific language) which allows Western-style music to be written using a tiny subset of commands:
... with quite a few options each. The output is sheet music (pdf) and MIDI.
This was an Android app which allowed you to use your phone to scan a barcode. From the barcode, it would find the issuing company and search with it on AgainstInequality, telling you who the parent company and owner of the product are along with some basic political donation information.
The idea was, you could scan a Twix or whatever and see who the ultimate owner was and see if the company is generally Republican or Democrat, whether they donate to Labor or the Chamber of Commerce, etc.
It died when the free barcode-to-company service I was using started wanting $500 / mo. Yeah, no, yeah.
This was a for-me-only app which pulled Yahoo Finance data (their API was the best) and allowed me to parse through it for deals. It was ruby and postgres.
This was a game for teaching the player new words and word roots. Essentially you'd memorize some word stems then words they're made up from, then match them up afterwards.
I actually loved learning word roots in high school English class, and incredibly they stuck in my brain ever since. They're still useful when trying to figure out the meaning of words in both English and other Romance languages. As an example, pretty much every spell in Harry Potter is made up of word roots, so if you're familiar you can easily figure out what a spell does by its name.
It was in Java. I hate Java, but it was the only choice for android apps at the time.
This was a before-its-time web page generator, much like what Drupal became. Via point-and-click, you could create a page and do a custom layout, with text and graphics, as though you were coding up a page with Bootstrap layout.
I got some devoted followers, but ended up taking it offline. There just wasn't as much usage, and certainly no path to profitability.
These are both from 2014, when I was living in the Bay Area and hiking and meditating all the time. That was a good way to live. I've written more stuff like this but these seem like the only ones I'm still OK putting out there.
In high school I wrote RPGs for TI calculators and Geocities sites. I wrote lots of tools for D&D including a cool dungeon generator.
In college I did ThoughtWeb, above, an auction app used by our local PBS affiliate during a telethon, surveys for my dad's job with the Area Plan Commission for St Joseph County IN, and many others I'm sure I'm forgetting.
Since 2001 or so I've also done zillions of apps for my job.
My absolute favorite ever was 4D Studio for DAQRI, a rails/angular app for which I was tech lead. Here's a demo from Augmented World Expo, I also created the valve demo being shown:
Before DAQRI I recreated kabam.com, a free-to-play game site for when those were all the rage. This was mostly a very successful PHP-to-Rails conversion.
Before that I worked on most of the Student Information System apps for the University of Chicago for 5 years. They were pretty simple, mostly PHP and MS-SQL.