A while ago I was enjoying PaperJS. It seemed like every time I searched for something to do with PaperJS, something else about RaphaelJS showed up. These two appear to be the major players in web drawing, at the moment. While PaperJS uses new technology (the HTML5 canvas element), RaphaelJS relies on SVG, making it compatible with older browsers (although apparently not with Android devices). The thing that I really like about RaphaelJS is that it’s very easy to export complex spatial shapes from ArcMap to SVG format, and use these shapes in a web drawing (I’m not sure of the easiest way to use a spatial shape in PaperJS). Here’s an example of mine, borrowed heavily from the RaphaelJS animation demos.