NiceDraw (N900 version)
(There is also an iPad version)
NiceDraw lets less experienced artists use a photo as template for their own drawings.
The unique feature is the slider, which allows you to change the brightness of the template quickly, to achieve a good visibility of template and your own drawing.
The slider is always accessible, as the brightness is often changed during drawing.
You will be surprised how nice your own drawings will be.
After two minutes it looks already as a drawing:-)