As a long-time fan of Edward Tufte's work, I've often wanted to make use of his sparkline idea, but haven't come across a suitable tool to make them. Now the GoogleChart API can generate these and a plethora of other chart types via a web service.
Here is an XQuery script to demo the interface, using the character-based simple encoding of the data:
I have one small problem - I don't know how to get rid of the axes.
I've just discovered the undocumented chart type lfi so the sparkline can be shown without the axes - I found out from Brain Suda's blog