Yahoo! User Interface Charts
The YUI Charts Control visualizes tabular data on a web page in several possible formats including vertical columns, horizontal bars, lines, and pies. Notable features include support for the DataSource Utility, customizable series and axes, a customizable mouse-over data tip, combination charts, and skinning.
Open Flash Chart
Open Flash Chart is open-source. It is free to use and you get the source code to fiddle with!
Why is that great? – When the user downloads the web page, Open Flash Chart requests the chart data from the server. The server knows who the user is so it can generate a chart for that particular user showing up to the minute data.
Timeplot is a DHTML-based AJAXy widget for plotting time series and overlay time-based events over them (with the same data formats that Timeline supports). Just like Timeline or Google Maps, Timeplot can be used with zero software installation, server-side or client-side.
You can populate Timeplot with data by pointing it to space or a comma-separated file (here is one of the data files for the timeplot above). Timeplot also supports Timeline’s XML format, meaning that you can reuse the same data file of your Timeline and overlay them over a time series plot (here is the event file for the timeplot above).
Chronoscope – Fly through your data with the greatest of ease. Turn your tables into time machines. Embed our widget into your web pages. Add it to your Google Spreadsheets as a Google Gadget. Plays well with the Google Visualization API.
SAC Simple Accessible Charts
Is the easiest, fast, accessible way to display simple Data and beautify them with CSS. It needed some time and a little bit of wired thinking, but It works. Works fine in FF, IE 7/6, Opera 9 tested on WIN XP.
The Dojo Charting Engine, courtesy of Greenplum and SitePen
Greenplum and SitePen announced the contribution of the new Charting engine to the Dojo Toolkit. Originally designed as the foundation for the Greenplum Monitor–a browser-based database monitoring application to be released later this year–the Charting engine is a cross-browser way of creating very complex charts easily, that can be updated on a regular basis.
and not to miss, check the Smashing Magazine post, these folks have done good research on “Modern Solutions for Charts And Graphs“.