Pet peeve: I really hate the “feature” of adding arbitrary (as in, not related to the data or any reasonable model of them) spline interpolation through data points to make them look “smooth”, especially for these charts that really should be bar charts (i.e. represent quantities of items).<p>Anyway, this sort of thing can be helpful for quick one-offs, but for anyone who runs into the limits of what a tool like this one can do, and needs something more customizable or sophisticated, remember to take a look at D3. It really is neat. <a href="http://mbostock.github.com/d3/" rel="nofollow">http://mbostock.github.com/d3/</a>