Bright and Shiny the All New Google Chart API

wow take a look at this tight little implementation! Nice concept, rapid return of the image and though it did not ship with sparklines support it will add it shortly...
Google Chart API

The Google Chart API returns a PNG-format image in response to a URL. Several types of image can be generated: line, bar, and pie charts for example. For each image type you can specify attributes such as size, colors, and labels.

You can include a Chart API image in a webpage by embedding a URL within an tag. When the webpage is displayed in a browser the Chart API renders the image within the page.