Balloon.css
Simple tooltips made of pure CSS
Bootstrap Tour
Quick and easy product tours with Twitter Bootstrap Popovers
Heatmap.js
JavaScript Library for HTML5 canvas based heatmaps
Flex Slider
An awesome, fully responsive jQuery slider plugin
Open Jscad.org
OpenSCAD + JavaScript = OpenJSCAD, edit locally or remote online, preview in browser direct via WebGL.
Prosemirror
The ProseMirror WYSIWYM editor
Datamaps
Maps for interactive data visualizations in Javascript
Tonal
A functional music theory library for Javascript
Colorbox
A light-weight, customizable lightbox plugin for jQuery
jQuery.nicescroll
nicescroll plugin for jquery - scrollbars like iphone/ipad
Odometer
Smoothly transitions numbers with ease. #hubspot-open-source
Zip.js
JavaScript library to zip and unzip files
Holder
Holder renders image placeholders entirely on the client side.
Ractive
Next-generation DOM manipulation
Intercooler Js
Making AJAX as easy as anchor tags
Touch Swipe jQuery Plugin
TouchSwipe is a jquery plugin to be used with jQuery on touch input devices such as iPad, iPhone etc.
Derby
MVC framework making it easy to write realtime, collaborative applications that run in both Node.js and browsers