Web visualization libraries What are some good visualization libraries for online use? Are they easy to use and is there good documentation?  
 A: IMO, Protovis is the best and is very well documented and supported.  It is the basis for my webvis R package.  
These are also very good, although they have more of a learning curve:


*

*Processing

*Prefuse
A: RaphaelJS can do some pretty amazing stuff and it just got some major backing from Sencha (formerly ExtJS).  Raphael is pretty smart about browsers by using a VML backend for Internet Explorer and SVG for everything else.  However, the library is pretty low-level.  Fortunately, the author has started another project, gRaphael, that focuses on drawing charts and graphs.
The MIT SIMILE Project also has some interesting JavaScript libraries:


*

*Timeplot

*Timeline
There is also a project to port Processing to JavaScript: ProcessingJS
Jmol is a Java applet for viewing chemical structures, but it is used as the display engine for 3D graphics in the SAGE system, which has a completely browser-based GUI.
And for an open source alternative to Google Maps, there is the excellent OpenLayers JavaScript library which powers the frontend of the equally excellent OpenStreetMap.
A: *

*http://insideria.com/2009/12/28-rich-data-visualization-too.html 28 Rich Data Visualization Tools

*http://www.rgraph.net/ R graph

*http://vis.stanford.edu/protovis/
A: There are hundreds of them. Here is a useful review of some twenty of them:
 http://bigdata-madesimple.com/review-of-20-best-big-data-visualization-tools/
A: I would recommend ChartJS, it's simple, beauty and well supported.
