Automatically hide or quit apps after periods of inactivity
Battery Thing
Show or hide your Mac's battery icon when you want
AutoMute
Silence your Mac automatically in class or at the office
Tockler
Automatically track applications usage and working time.
Bartender 2
Organize and hide menu bar items on your Mac
IntelliDock
Automagically hide & show macOS' Dock
Quitter for Mac