Ask HN: What's the most creative 'useless' program you've ever written?

I once coded a machine that could make photo-books of your neighbour's living rooms.

It was inspired by Ed Ruscha's "34 Parking Lots in Los Angeles" artist booklet from 1967, and the output looked pretty similar, but with photos of domestic interiors instead of parking lots. So far so ordinary, but the difference was that you could tweet any UK postcode at the machine and a couple of minutes later it would spit out a custom-generated, printed-on-demand booklet of living rooms in that neighbourhood.

The way it worked was when it received a postcode, it went to Gumtree (popular UK second hand listings site) and looked for second hand sofas for sale within a radius of 1km. It then scraped the photos, imported them into a document, generated a PDF on the fly and sent it to a laser printer with a built-in binding machine. The results were insanely good. Always hoped I'd get to show it to Ed Ruscha one day.

The project was commissioned by the Victoria and Albert Museum in London, but still kind of pointless from a utilitarian point of view :)

[1] https://gagosianshop.com/products/ed-ruscha-thirtyfour-parki...

Many years ago, I made an emacs script that plays back diffs between files as live edits in the emacs buffer: https://github.com/nma83/diff-actor

My nefarious intent was to make my screen at work look like I am editing code from remote login :). PS: the aciinema link for the demo video is dead right now.

This wasn't super creative, but way back in time, I was on a local tinymud and a number of us starting writing bot NPCs for it. I built a bartender bot that eventually would remember drinks, tell jokes, and more. One day another bot came into the bar and got into an extended exchange of insults with the bartender bot. We were kind of dumbfounded watching these blocks of switch statements have a very real-looking conversation in front of us.

I used to write PostScript programs to draw stuff (usually just fractals) on paper.

PostScript is a Forth dialect, so you can do quite a lot with it. If you had a printer that supported PostScript, you could pipe the source code straight to lpt1 (or wherever), and the printer would execute the program directly. It was fun to see what I could get to execute on printer hardware, which was generally fairly limited.

Very long ago, I wrote an interpreter in PHP for an arbitrary syntax that was essentially a subset of PHP. It had loops, recursive functions, and performed calculations with BC math (basically using strings for mathematical calculations instead of primitives since it had fewer capacity limits. No practical reason for it though). It taught me a ton about tokenization and how precedence works in an interpreter

I also made a simple mod tracker in JavaScript. It didn't use the audio API. It worked by changing the frequency of header values in WAV files it had embedded within it to play different notes from a sample. Surprisingly it actually changed pitches properly. But the embedded nature made it unfeasible to keep or play more than two samples at a time. It was a good lesson in editing binary, file formats, and browser limitations