CodeKit - CodeKit allows you to optimize the performance of your website by automatically and efficiently compiling a variety of popular languages.
Fire.app - Fire.app is a menu bar only app for dead easy HTML prototyping.
Prepros - Compile Less, Sass, Scss, Stylus, Jade, Coffeescript, Haml and Markdown with live browser refresh.
SassMeister - The sassiest way to play with scss/sass, compass, & LibSass.
Scout-App - Process Sass files into CSS without any knowledge of the command line.
Javascript Packer - JavaScript-Packer has 26 repositories available. Follow their code on GitHub.