Natural Language Processing:

 * ALE (Attribute Logic Engine) is a freeware system written in Prolog
   that integrates phase-structred parsing, semantic-head-driven generalization 
   and constraint logic programming with typed features such as terms.
   You can find ALE at http://www.sfs.nphil.uni-tuebingen.de/~gpenn/ale.html
   The site http://www.ltg.hcrc.ed.ac.uk/projects/ledtools/ale-hpsg/ details
   how to build an NLP grammar using a head-driven phase structured grammar
   (HPSG) and ALE.

 * Eric Brill's trainable rule-based part of speech tagger (version 1.0.2)
   is available by anonymous ftp from 

      ftp.cs.jhu.edu:/pub/BRILL/Programs/

   This tagger is based on transformation-based error-driven learning, a
   technique that has been effective in a number of natural language
   applications, including part of speech and word sense tagging,
   prepositional phrase attachment, and syntactic parsing.  For more
   information, you can obtain relevant papers in 

      ftp.cs.jhu.edu:/pub/BRILL/Papers/

   If you do download the tagger and wish to be on the mailing list for
   future releases, bug reports, etc, please send mail to Eric Brill
   <brill@cs.jhu.edu> or <brill@goldilocks.lcs.mit.edu>.

 * Hdrug is an environment to develop logic grammars, parsers, and
   generators for natural languages.  The package comes with a number of
   example grammars, including a Categorial Grammar, a Tree Adjoining
   Grammar, a Unification Grammar in the spirit of Head-driven Phrase
   Structure Grammar, an Extraposition Grammar, a Definite Clause
   Grammar, and a port of the HPSG grammar from Bob Carpenter's ALE
   system. Each of the grammars comes with a set of parsers, such as 
   Earley-like chart parsers, left-corner parsers and head-driven
   parsers. Some grammars come with variants of the head-driven
   generator. The package allows easy comparison of different
   parsers/generators, extensive possibilities of compiling feature
   equations into Prolog terms, graphical (Tk), LaTeX and ordinary Prolog
   output of trees, feature structures and Prolog terms, and plotted
   graphs and tables of statistical information. Hdrug runs in Sicstus
   Prolog and requires ProTcl and Tcl/Tk. It is available by anonymous
   FTP from

      ftp://tyr.let.rug.nl/pub/prolog-app/Hdrug/

   or by WWW from

      http://tyr.let.rug.nl/~vannoord/prolog-app/Hdrug/

   For more information, write to Gertjan van Noord <vannoord@let.rug.nl>.

 * NLBean(tm) version 2: a natural language interface to databases. 
   It is an example of conversion of natural language from a limit domain
   to SQL querries for database access.  Go to http://www.markwatson.com

 * Grok is a project dedicated to developing a large collection of
   basic tools for NLP.  See more at

      http://grok.sourceforge.net