I have also charted the first preferences votes over the past four elections (the Liberal / National coalition were in power from 1996 until 2007).
Looking again at the chart API, if you check the properties of these charts then you can see the url parameters used to create them. This means that if you like a chart that someone else has created, you can copy and modify it at your leisure. That is, you don't just have the image of the chart to play with, but everything used to create that chart too.
As you'd expect from Google, the API documentation is complete and straightforward, and liberally sprinkled with examples. Even so, I'm sure it won't be long before some industrious developer builds a user-friendly web front-end, so that even the most timid of users could easily create a handy chart.