Web-based Data Visualization Library
bokeh - an interactive visualization library for modern web browsers.
The D3.js
Google Chart
Shiny - an R package that makes it easy to build interactive web apps straight from R.
Utilities
Mr. Data Converter - input: CSV or tab-delimited data. output: JSON/XML/Python/HTML.
Books
[Book] Interactive Data Visualization for the Web: An Introduction to Designing with D3
參考資料
60+ useful graph visualization libraries