Allows for loose syntax media queries with predefined breakpoints or custom, on the fly ones. Defaults to only screen and min-width, allows for those to be overridden. Can be expanded more.
Sept. 11, 2013 - Updated to include chained media queries, ie:
@media only screen and (min-width: 500px) and (max-width: 600px){}
A Pen by Stuart Trann on CodePen.