1. A simple service which notifies you about tips through various channels (slack, email, telegram). It rotates through a list of your tips that you've created. These could be programming tips, quotes etc,.
2. A service which sends you a kindle document containing all your pocket links every week.
3. A service which converts an open source code repository into a readable ebook which can be read on a Kindle like device.
4. A service that allows you to create a private website and share it with only a few users (authentication via email).
5. A simple blogging engine driven by a Dropbox folder and Markdown.