Visulization software: processing, D3.js, statistics R and matplotlib

Processing is a programming language, development environment, and online community. Since 2001, Processing has promoted software literacy within the visual arts and visual literacy within technology.
http://processing.org/

D3.js is a JavaScript library for manipulating documents based on data.
 http://d3js.org/

 matplotlib is a python 2D plotting library which produces publication quality figures in a variety of hardcopy formats and interactive environments across platforms
http://matplotlib.org/ 

R is a free software environment for statistical computing and graphics.
http://www.r-project.org/