I want to work with non-linear objects like arcs, circles, ovals, etc. However, I'd like to avoid all the trigonometry and floating point calculations. We can approximate these points by creatively iterating with integers by using Bresenham's algorithm to generate each point in the path.
With some of these tools, I can now investigate all kinds of other fun things like non-linear path animation, hits areas that are not boxes, etc. I know that as more and more developers dig into building with the capabilities of HTML5, some really powerful libraries will evolve.