Computational Lexicography

PyWordNet
A Python interface to the WordNet lexical database. (Also see JWordNet for a Java implementation.)
PyFSA
A library for manipulating Finite-State Automata (FSAs). It contains algorithms for constructing, minimizing, and determinizing FSAs, compiling them from regular expressions, and using them as rules in a chart parser.
ChartParser.py (view source)
A simple chart parser (<100 code lines for the parser itself).