Some folks have managed to implement gauges via clever occlusion of pie charts with other layout objects. If you have any skill with HTML, I'd recommend that you look into rendering the gauge in a web viewer rather than a chart object. The web viewer will give you more flexibility to look the way you (your client) wants.
I saw a cool round gauge graphic at last Devcon using Flash in the web viewer that had animation so you saw the gauge rev up. Pretty slick if you have a Flash developer that knows how to do that stuff.
Along the lines of cool examples for this sort of thing, the stuff at http://highcharts.com looks really impressive.
One sample that they have for a "speedometer" type gauge is at:
Perhaps that sample can provide some inspiration.
Edit: Fixed URL that I mis-typed.
If you're familiar with it (it's what I use for webviewer charts), google charts API also has a gauge view:
steve's example though has a convient link to load the code to JsFiddle though, which is extremely useful for tinkering it to your needs.