Library book renewals. I have an AWS Lambda function that runs daily, scrapes html from my public library (they have no API), and if a book is due within the next day, renews it. If I've reached max renewals, it sends me a notification.
https://github.com/pisomojadogrande/fcpl-api. Was a little weekend project, so not at all polished or documented, and only does a single account, but has a template where you could deploy it in your own AWS account. Also, the HTML scraping works only if your library is Fairfax Co., Virginia. But hopefully the pattern will be helpful.