http://d3js.org/
http://abgne.tw/tag/d3-js/page/2,
http://raphaeljs.com/,
http://net.tutsplus.com/tutorials/javascript-ajax/an-introduction-to-the-raphael-js-library/,
http://raphaeljs.com/reference.html,
http://chimera.labs.oreilly.com/books/1230000000345/ch01.html