Other related projects you may be interested in.

Sparklines a PHP library that makes tiny graphs which are ideal for placing in titles or text.

Graph geeks bible, less is more. Effective visual communication of data.

http://en.wikipedia.org/wiki/Pareto_chart, combination of bar and line chart showing the 80:20 rule.

The Long Tail.

SWFObject.

I find choosing colours that compliment each other rather daunting. Try this: eye pleasing colours.

An open source PHP graphing system: graidle.

Flash guages: SWFgauges 1.0.

five3d looks interesting.

How to draw nice charts: Edward Tufte, The Visual Display of Quantitative Information