Designed to keep you sane while working on different copies of your site (Development, Staging, Production, etc.), Environment Indicator adds some visual cues (currently only changing the background color of the toolbar) to indicate which copy of the site you are interacting with.
This is incredibly useful if you have multiple environments for each of your sites, and like me, are prone to forgetting which version of the site you are currently looking at.
No special requirements.
This module has been based on https://drupal.org/project/environment_indicator.