PyLint - An extensible tool that checks if a module satisfies a given coding standard. - http://www.logilab.org/857/
twill - A tool for Web application testing. It implements a simple scripting language that can be used interactively or from scripts; this language contains commands for browsing the Web, filling out forms, and asserting various conditions. - http://twill.idyll.org/
Shed Skin - Shed Skin is an optimizing Python-to-C++ compiler. It accepts pure, but implicitly statically typed Python programs. Programs typically become 2-40 times faster than with Psyco. [Open Source, GPL] - http://mark.dufour.googlepages.com
PyUnit - An extensible unit testing framework for Python, based on Java's de facto standard JUnit framework. - http://pyunit.sourceforge.net/
PyChecker - A tool for finding common bugs in Python source code. It finds problems that are typically caught by a compiler for less dynamic languages, like C and C++. [Open Source, BSD-like] - http://pychecker.sourceforge.net/
Psyco - Specializing (like a dynamic) compiler for Python, runs code 2-100 times faster, needs much memory; makes high level language faster. Descriptions, downloads (program, website), documents, news, links. [Open Source, MIT] - http://psyco.sourceforge.net/