No mention of dygraphs either, although it is only for time-series data. http://danvk.org/dygraphs/

Good post covering all the popular javascript plugins for different libraries. Definitely want to see or build a Raphael library. Who's in?

There is a graphing library for Raphael. Last I checked it didn't seem very mature, but it might make a good starting point:

http://g.raphaeljs.com/

I've got a fairly complete one: http://github.com/Kilian/ico

It uses Raphael and Prototype, and has some interesting options that most other libraries don't have (such as stacked area charts)

No Bluff? MIT license, and the only dependencies are JS.Class and ExCanvas (both are bundled with it).

http://bluff.jcoglan.com/

As soon as you need to embed an image of the chart in a pdf you may run into issues with these libraries.

It's been my experience users always end up wanting to save the image for a presentation or report.

Agreed. We had the same problem with flash charts, it was like the most requested feature so we just ripped them out and replaced with a server side generated chart.

I quite like OpenFlashChart (which uses JSON as an input format, though that JSON is typically made with a server-side language).

I use the Python bindings (which use Chart objects) and the output generally works with my brain. Users like that mouse-overs give exact values in the line at that point.

Thanks everyone for enriching this list. You may find useful my delicious list: http://delicious.com/robicch/chart

Anyone know of a chart lib that will do three or more y-axis, or a way to hack in three or more axis?

The jqplot library mentioned seems to do it.

http://www.jqplot.com/tests/multipleYAxesTests.php