The Cyril programming language is designed for fast prototyping of visualisations and live coding visuals.
New site: Cyril user Dan has created a blog with useful examples for learning Cyril - Cyril Patterns
Cyril at Reasons to be Creative:
Cyril at Manchester Algorave blog post from Cyril user Dan Hett about his use of Cyril at the Manchester Algorave
See some examples below, or checkout these examples by Cyril user Dan Hett
More example videos on Vimeo
Cyril FFT Test:
Cyril Live Coding example: