PlotKit - Javascript Chart Plotting. PlotKit is a Chart and Graph Plotting Library for Javascript.
It has support for HTML Canvas and also SVG via Adobe SVG Viewer and native browser support. PlotKit is fully documented and there is a quick tutorial to get you started. PlotKit is a complete rewrite of CanvasGraph. Free online diagramming application. Projects: Open Flash Chart Plugin for Ruby on Rails - Graphs. Note: Version 2 of Open Flash Chart is available.
Examples for version 2 are here. I ported the php code for open flash chart to ruby and so far it has worked quite well with Rails.Just ported the latest 1.9.7 version - see the many graph examples below.