Flash is an excellent technology for dealing with data visualization. It being client-side, it can reduce the amount of work your server has to perform in order to generate graphs and charts. Because of its robust ability in dealing with sleek and fluid animation and complex user interactivity, Flash is an excellent web and (and even desktop) application technology for dealing with graphing data.
1. Open Flash Chart
Open Flash Chart is an open source Flash-based graphing and charting solution developed using ActionScript 3 and compiled using Flex. Open Flash Chartís features include interactivity of your charts with tooltips, the ability to resize your charts client-side, and being able to save your graphs as images.
2. XML/SWF Charts
XML/SWF Charts is a powerful Flash component for creating interactive graphs and charts. With XML/SWF, you can use XML to describe the data youíre wishing to plot, making it easy to create dynamically-generated and easily-maintainable Flash charts (i.e. you need only to alter the XML file instead of having to use Adobe Flash application). Check out this basic tutorial to get you up and running right away with XML/SWF Charts.
AmiChart has a 15-day free evaluation which gives you unfettered access to all its features. A single-user license costs $39.