Grafica library
It's possible to have multiple data sets (layers) in the same plot. It's also possible to display them with different properties.
In this example we have two layers. We are drawing the points from the first layer as red circles, and those in the second layer as a closed filled contour. The points from the first layer are updated every few frames. Drag the plot area with the mouse to pan. Click to change the point rotation.
For more details, check the source code or play with it at JSFiddle.