LinkParser

 LinkParser is a syntactic parser by Davy Temperley, Daniel Sleator and John Lafferty of Carnegie Mellon University.  It is being ported to Ruby by Martin Chase.

There is also  a binding under development for the  improved link-grammar library created for AbiWord. That's what I use for testing and for my own projects. There are other bindings for link-grammar, but they are untested and may not be API-compatible with this library.