One of the new features in ArtRage is the ability to use stencils. Very clever.
Morpheus is a program that allows you to take two images and create a controlled
morph from one to the other..
SketchUp is a powerful, but free, program from Google that is used to make 3D
objects and environments.
After being in development for years, Processing has been released as version 1.0.
It was originally developed to help artists understand programming, and has
developed into a tool with many artistic, educational, and other uses. It's free.
More Software
ArtRage, a natural-media drawing and painting program, is in version 2.5.