It's probably not what you meant, but I recently created a weekend project bot that scans facebook for apartments rental ads.
Thanks to this bot, I landed an opportunity I wouldn't have catch otherwise, saving me 6,000$ a year.
Assuming I will hold my new apartment for 3 years, this is a net savings of 18,000$.
I haven't sold anything, but yet I created something that "generated money" for me.
My code is open source by the way, and I wrote about it here: https://snir.dev/blog/apartments-bot/