The most useful one is an invoice generator that looks at a bunch of Markdown files of work I've done for clients (I'm a freelance writer) and generates an invo

The most useful one is an invoice generator that looks at a bunch of Markdown files of work I've done for clients (I'm a freelance writer) and generates an invoice from them. It can either generate an HTML report with various stats and graphs or create a draft invoice in Freshbooks for sending to the client. It used to take me a couple of hours a week to invoice, and now it basically takes no time at all. I can't really share it because it's got some hardcoded client details, but I'm considering generalizing it into a txt2invoice utility other people can use. It's also massively over engineered because I used it as a learning project for Elixir. Every time I learned how to something new I tried it out on this tool, which means it spins up lots of processes it doesn't need and does fancy stuff with messaging, genservers and supervision trees which are entirely unnecessary, but that's part of the fun.