Old news to many, but Google has a Charting API that allows the creation of numerous chart types via a formatted URL string. The Google Chart API returns a .PNG file which is easily embedded in an image tag. If you want to embed charts into your web applications, this chart API might help get you to market quicker.
The idea is simple enough - create an API which returns an image given a specially formed URL. Values can be specified in-line, or encoded to make them more manageable. There are too many chart types and options to document here, but Google's documentation for this API is pretty extensive. I'm impressed with the approach and simplicity. I'm also impressed with the breadth of chart types and the number of options available. In general - they just look plain cool!
Although the API is pretty easy to drive natively, there is also a .NET Helper Library called ngchart which simplifies the API's from native .NET code.
Enough talk - some examples -