Google just released a Chart API. It lets you link to a dynamic image which can then be used to generate graphs and charts. The API is amazingly robust. It supports all sorts of charts. It lets you make an image like the one below using a simple URL (see the image URL for an example):
Why is this better than hosted solutions? For 99% of web masters out there, Google’s up-time will beat the pants off of them. There’s really little to no question about the availability of their solution. Not to mention if it’s really an issue, these images could easily be cached by your application after generating them. The biggest draw, of course, is that unlike other hosted solutions, this one doesn’t use proprietary formats (flash), doesn’t introduce security vulnerabilities (for installing some foreign server-side package), and doesn’t add CPU or memory overhead to your application.
“To control and organize the world’s information.” This project is certainly a reflection of their motto.