D3.js - D3.js is a JavaScript library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG, and CSS.
The Data Visualisation Catalogue - Reference tool for data visualisation
Highcharts - A charting library written in pure JavaScript, offering an easy way of adding interactive charts to your web site or web application
Flourish - Powerful, beautiful, easy data visualisation
Chart.js - Easy, object oriented client side graphs for designers and developers.
nivo - nivo provides a rich set of dataviz components