Mincss
Tool for finding out which CSS selectors you're NOT using.
Drawingboard.js
A canvas based drawing app that you can integrate easily on your website.
q Tip2
qTip2 - Pretty powerful tooltips
Turn.js
The page flip effect for HTML5
Swig
Take a swig of the best template engine for JavaScript.
Sprite.js
An efficient javascript sprite animation framework
Muuri
Responsive, sortable, filterable and draggable grid layouts
Mobx
Simple, scalable state management.
Clusterize.js
Tiny vanilla JS plugin to display large data sets easily
Anijs
Declarative handling library for CSS animations.
Trial Js
Mouse position monitoring and user input prediction
Js Cache
jsCache is a javascript library that enables caching of javascripts, css-stylesheets and images using my localStorage polyfill. This is especially useful when serving your website for mobile phones, which have limited HTTP caching available, but also speeds up your site in an ordinary web browser as it saves HTTP requests and loads all files asynchronously.
Typecast.js
Typecast.js :: Solving the simple problems
Queen
A platform for running scripts on many browsers
Upfile
Makes file inputs a pleasure to use with progressive enhancement.
Kefir
A Reactive Programming library for JavaScript
Highway
A fast, lightweight and simple Javascript routing library with no dependencies.