Reliable / Popular data visualization toolkit for the web

I'm looking for a reliable toolkit in any web-neutral[A] language, actively maintained / developed, stable that allows me to build graphs, charts, display data dynamically, allow drag-n-drop of datasets and refreshes automatically.

Carlos Scheidegger recommended - http://vis.stanford.edu/protov开发者_运维问答is/ which looks great! But I'm looking to see what others are there and what ppl are using...

[A] What I mean is something like js / jquery, etc. which can be generated by any web language like php, python, perl, etc

Check out the MIT Smile project, RGraph, and of course Processing (if you are willing to deal with applets).

Raphael is also a good option.

You might want to check out Google Analytics, Yahoo Web Analytics, Omniture SiteCatalyst, or Webtrends.