SOFA Statistics
From http://www.sofastatistics.com/
SOFA is a user-friendly statistics, analysis, & reporting program. It is free, with an emphasis on ease of use, learn as you go, and beautiful output.
PuLP
PuLP provides linear programming in Python. Its website is http://code.google.com/p/pulp-or/ and is the basis for several courses at the University of Auckland.
SimPy
SimPy is a simulation package for Python. Visit its webpage at http://simpy.sourceforge.net