In my band ORM, we sell quite a bit of merchandise at many of our shows. Manually keeping track of sales and inventory turned into quite a time consuming chore over time. We could have moved our merch off of Bandcamp, but Bandcamp remains a great place to drive sales and get exposure.
While in the tour bus, I hacked together a quick app to automate some of the tedious work. Amazingly, it worked quite well, and the first prototype for Packrat was born. Since then, I've spent a sizeable chunk of my precious free time developing and improving the app, so that others in the same situation could benefit from the hours I've put in.