I encourage everyone to rush and download ArtRage, the free natural-media paint program from Ambient Design. One never knows how long a generous company will prolong its generosity, and ArtRage offers a variety of top-notch tools for the unbeatable price of naught. (I was hoping Pippa would like it as much as it turns out that she does!)
My only desideratum would be a slight tweak of the trace tool (which Pippa used in painting this portrait of my beloved). In its present iteration, the trace tool reproduces across its whole width and stroke the color it finds at its starting point. It would be truly niftily handy if one could use the paint tools to apply stroke and paper texture, but have the color change with the color of the underlying photo (I believe Painter does this, or used to). But zowie, this is a very slick tool.