EdwardBock

Show environmental info on your admin bar so you will never accidentally edit production site contents instead of stage or the other way around.
<h3>Arbitrary section</h3>
There’s a documentation at https://github.com/palasthotel/wp-environment-info

Environment Info

Show environmental info on your admin bar.

cleanscript

A very simple plugin that provides information about the Custom Page Templates available in the theme: What they are, which are not used and where the used ones are used, selectively.
Main features: 
Available page templates list 
Unused page templates list 
List of page templates with checkboxes that output when submitted the links where they are used

Cleanscript – Page Templates Info

Find information about your page templates. What they are, which are not used and where the used ones are used, selectively.

Environment Info vs Cleanscript – Page Templates Info