I am happily trying out protovis (renders as SVG): http://vis.stanford.edu/protovis/ex/ I am confused now about canvas: this article says a downside is redraws, but http://thejit.org uses canvas, stating that it is better for animation.
I've read the difficulty is that you need to manage redraws yourself:
https://developer.mozilla.org/en/Canvas_tutorial/Basic_anima...