For those of you that don't know, Google has a free charting API.

The charting API, which is based on URL construction, is quite powerful.

Dealer Diagnostics figured out how to make nice looking bullet charts using the API.

Because the Google API creates an image you can use in a standard <img> tag, you can integrate it into any reporting tool that allows you to construct HTML elements. For example, if you've ever played with "microcharting" in Cognos Report Studio, you'll find that you'll spend more effort than it's worth fine tuning the charts. In some cases, it would be easier to simply use the Google Charts API instead.