Topfunky-sparkline-js is a project mainly written in JavaScript, it's free.
Sparkline graph library using Raphael.js
A Javascript library for creating small but informative graphs with Javascript.
Requires the Raphael SVG drawing library.
Can be used with Cufon for font drawing.
Geoffrey Grosenbach PeepCode Screencasts
See the example page
TopfunkySparkline("my_canvas_element", [1,2,3,4,5], {width:400, height:30, title:"A Chart"});