Handling the multiple copies of Drupal's settings.php file needed for each site, between the development, staging, and live environments, can be a bit of a hassle. Database settings and other configurations almost always vary from environment to environment so having a simple way to manage these differences would be fantastic. Always on the look out for work-flow improvements, I had heard about this gem at DrupalCon Denver in March but had yet to implement it in any of my projects.