Because I was tired of the endless iterations about the set list in case of an upcoming gig of my acoustic band, this week I made a set list generator for myself and my band mates on our web site.
The initial song list is rendered from our @getkirby cms, then sortable.js is thrown at it. The customised list is stored locally in localStorage and can be shared or printed via the browser's dialogue print->as pdf. The nice thing here is that the list will "survive" a page reload and even closing the page and coming back later, as long as the localStorage isn't cleared.
Now everyone can bring their idea of the upcoming set to the next rehearsal. hah.
This started as a "hm, lets see if this works" prototype, and now that the idea is working I have lots of ideas and refactoring up ahead. (sharing the list via link, switch from jQuery to vanilla, store several lists locally, make it work offline etc pp) 
This has been a fun excercise mainly due to the fact that I didn't know where it would end. This went from idea to prototype to kind-of-production and with each step new possibilities and ideas emerged, throwing away some stuff, adding new stuff, refactoring and changing as needed.
This is my favorite way of working. Instead of having a clear picture of the outcome in mind, having an idea of what it should do basically, but get to that point as early as possible and then iterate on that.