D3.js is a small, free JavaScript library for manipulating documents based on data.
Free, Open-Source Data Visualization Web Widgets, and More
Interactive Geometry, plotting, visualization
JSXGraph is a cross-browser library for interactive geometry, function plotting, charting, and data visualization in a web browser. It is implemented completely in JavaScript, does not rely on any other library, and uses SVG, VML, or canvas. JSXGraph is easy to embed and has a small footprint: less than 100 KByte if embedded in a web page. No plug-ins are required! Special care has been taken to optimize the performance.
Notificon is a BSD licensed javascript class for providing client-side favicon notifications. Instead of requiring a number of favicons be created and served up to the client, you can specify a label and a favicon (default being the current favicon) and it will generate a favicon notification.
A finite state machine javascript micro framework
The jQuery plugin for doing cool scrolly stuff
Impressive JS/CSS3 presentation toolkit
“generators + promises = tasks
task.js makes sequential, blocking I/O simple and beautiful, using the power of JavaScript’s new yield operator.”
Uri parsing, modification, query string manipulation and high-fidelity re-stringification in javascript.