Since I posted early last year about Edward Tufte's Sparklines, the paper was updated and some implementations have sprung up (via Sam Ruby):

• James Byers wrote a PHP version of sparkline which unfortunately hasn't been updated since last November.
• Joe Gregorio has a Python version of sparkline that works only for Firefox.
• And here is a Ruby version of sparkline.

I think the most important aspect of sparkline is the seamless inlining of graphics with text, so sparkline graphics should be resized automatically when the size of the surrounding text changes. I am not sure Mozilla/Safari's canvas tag can do this yet but I hope it does before the canvas tag becomes a de-facto standard.