If anyone is interested, I have created a few apps to perform some basic, but often repetitive tasks. The apps are:
Simple Contact Reminders
This application provides a simple reminder notification system for contact sensors (doors/windows/etc.) that have been left open.
Simple Switch Reminders
This application provides a simple reminder notification system for switches that have been left on.
Simple Switch Off Timers
This application provides a simple switch timeout system for turning off switches that have been left on. Sometimes people refer to this as an "Egg Timer".
None of these applications do anything you cannot do with Rule Machine (I mean, what can't you do with Rule Machine?), but they are a lot simpler and easy to manage, especially if you have dozens of entries.
Code can be found here: GitHub - dennypage/hubitat: Hubitat drivers and applications. Comments welcome.
Update Dec 29, 2020:
I have added another application to the series:
This application provides a simple alert notification system for devices that have not been updated for a period of time. This is useful for ensuring devices that are expected to periodically report status, such as temperature sensors, do not silently go offline. I also use it to alert me if my weather information goes stale.