Updated 26 Mar 2016 for Brunch 2.0
While working at OnTrees I was introduced to brunch by @_grayham and have used it on a couple of my own projects (more recently exploregiving.com). Brunch is an alternative front-end build system to Grunt or Gulp.
You can achieve the same thing with any of these front-end build systems. I’ve just found the brunch conventions and workflow very simple to work with. What closed it for me was how easy it was to add brunch to our continuous deployment pipeline.