TraceKit : Not all browsers support stack traces on error objects, but TraceKit squeezes out as much useful information as possible and normalizes it.
Photon : UI toolkit for building desktop apps with Electron.
Tracery : A story-grammar generation library for javascript. Write grammar objects, get generative stories.
Head JS : Load scripts like images. Use HTML5 and CSS3 safely. Target CSS for different screens, paths, states and browsers. Make it the only script in your HEA...
enquire.js : A lightweight, pure JavaScript library for responding to CSS media queries.
Add Clippy or his friends to any website for instant nostalgia.