Google Chart Tools/Image Charts (aka Chart API)
The Google Chart API is an extremely simple tool that lets you easily create a chart from some data and embed it in a webpage. You embed the data and formatting parameters in an HTTP request, and Google returns a PNG image of the chart. Many types of charts are supported, and by making the request into an image tag you can simply include the chart in a webpage. You can embed these charts on your web page, or download the image for local or offline use.