RubyGems.org

Using this package, you can do powerful pattern recognition easily from your shell command line using a simple suite of tools. Applications include music cateogrization, text classification, handwritten digit recognition, and evolutionary tree reconstruction. The technique is based on a very general theoretical notion of Kolmogorov Complexity, and so is undoubtedly applicable to many as yet unknown disciplines. See the webpage for research papers explaining the math behind these techniques.