Lush
Lush (Lisp Universal SHell) is a Lisp dialect that features tight integration with C and bindings to a lot of numeric and linear algebra libraries. According to the Lush homepage:

If you do research and development in signal processing, image processing, machine learning, computer vision, bio-informatics, data mining, statistics, simulation, optimization, or artificial intelligence, and feel limited by Matlab and other existing tools, Lush is for you. If you want a simple environment to experiment with graphics, video, and sounds, Lush is for you.

Homepage: http://lush.sourceforge.net/index.html

License: ???