XML driven components are a favorite among designers of dynamic Web sites. They allow to dissociate content from rendering, and greatly facilitate the site maintenance. The most popular are Flash charts, although other technologies are available, like Silverlight.
In addition, and it is actually the point of this post, SharePoint offers a convenient way to update xml files: the Data Form Web Part. Note that setting up a Data Form Web Part requires SharePoint Designer.
Maybe you didn’t know that XML files could be edited directly from within SharePoint pages? If so, the demo page also includes a tutorial on how to set up the Data Form Web Part using SharePoint Designer.
XML files vs. SharePoint lists
Instead of an XML file, another standard approach is to store the data in a SharePoint list. You can then pull the list content in XML format to render the chart.
The advantage of XML files is that they are easier to set up. It just takes a couple minutes to upload the file to SharePoint and link it to a Data Form Web Part. With a SharePoint list, you would have to write the code that grabs the list XML and transforms it into a format that the component can read.
On the other hand, the list approach will be better if you want to benefit from specific SharePoint features (e.g. alerts, version history and permissions at the item level).
My live demo is sponsored by FusionCharts (version 3). Note that the previous version, FusionCharts v2, is available for free (22 chart types).