Generating Graphs with PHP and Google Charts API
Ludwig Pettersson has a really good overview of the Google Charts API, and how you can integrate your PHP scripts with it. He created a PHP library that wraps around the API, and makes it really easy to generate graphs that way.
I’m not sure if I would move away from JpGraph to this new library, but it seems really cool no matter what. I guess it could be an option if you wanted to avoid doing all of the manual work associated with different types of graphs, and offload some graph generation to Google.