Just a very simple Python script (that depends on Node executables :p) to concatenate JS/Coffeescript files and compress them. I run a Procfile with Foreman that runs this python script on the js/ directory in small projects + stylus on the .styl files. It's similar to some functionality of Brunch.io but where Brunch is not suited I needed a small wrapper to do this for me.
chmod +x watchjs.py
./watchjs.py <directory> <output filename>