Google have expanded their API collection to include fantabulous real time, dynamic charting. They announced it today on the Google Code Blog.
Putting this into your img tag or browser: http://chart.apis.google.com/chart?cht=v&chd=t:40,40,40,10,10,10&chs=250x150&chdl=Google|Charting|Awesome
Will produce this:
It's the same technology they use in Finance and Video, so it's nice to see them make it available for all of us. It currently supports line chart, scatter plot, bar chart, Venn diagram, and pie charts.