Digital Art Software showdown:
Processing is a Java-based environment for creating digital art. ProcessingBlogs often showcases examples of Processing creations. This Flock of birds demo and the Webcam controlled video pong are nice examples.
VVVV is a realtime video synthesis framework. It is a Windows only flowgraph based system, which seems to be built on top of DirectX and DirectShow. As seen on the Eno Henze image above, VVVV is also very suitable for creating static pictures.