Python – An overview for beginners

Python Package Manager

setuptools
easy_install
pip

Python web application frameworks

django    
Django is a high-level Python Web framework.
http://www.djangoproject.com/

web2py
An open source full-stack python web framework for scalable, secure and portable
web applications. http://www.web2py.com/

flask
A lightweight Python web framework based on Werkzeug and Jinja 2.
http://flask.pocoo.org/

grok
An open-source Web framework based on Zope Toolkit technology.
http://grok.zope.org/

tornado
Tornado is a scalable, non-blocking web server and web application framework.
http://www.tornadoweb.org/

cherrypy
CherryPy is an object-oriented web application framework.
http://cherrypy.org

turbogears
A Python-based database web app framework with Ajax integration.
http://www.turbogears.org

google app engine
A platform for developing and hosting web applications in Google-managed
data centers, including Python. https://developers.google.com/appengine/

pylons
A lightweight web framework emphasizing flexibility and rapid development. 
http://www.pylonsproject.org/projects/pylons-framework/about

Full List:
http://wiki.python.org/moin/WebFrameworks

Python Checkers / Debugging

Pychecker
A tool for finding bugs in python source code.
http://pychecker.sourceforge.net/

pudb
PuDB is a full-screen, console-based visual debugger for Python.
http://pypi.python.org/pypi/pudb

pdb
The module pdb defines an interactive source code debugger for Python programs.
http://docs.python.org/2/library/pdb.html

pylint
Analyzes Python source code looking for bugs and signs of poor quality.
http://www.pylint.org/

Full list:
http://wiki.python.org/moin/PythonDebuggingTools

Python shell

dreampie
A graphical interactive Python shell which is designed to be reliable and fun.
http://www.dreampie.org/

ipython
A development shell both written in and designed for Python.
http://ipython.org/

bpython
A fancy interface to the Python interpreter for Linux, BSD, OS X and Windows.
http://bpython-interpreter.org/

Python Game

PyWeek
programming challenge that produces several great games.
http://www.pyweek.org

Pygame
Home of the PyGame module and a portal with links to lots of Python games.
http://pygame.org

Full List:
http://wiki.python.org/moin/PythonGames

CMS

Skeletonz
Simple, powerful, extensible, reliable. Ajax based editor with spell checking
& UTF-8 support.
 http://orangoo.com/skeletonz/

Mezzanine
A powerful, consistent, and flexible content management platform.
http://mezzanine.jupo.org

Django
Django offers elementary support for content management.
https://www.djangoproject.com

Ikaro
Offers content management functionality.
http://www.hforge.org/ikaaro

Kotti
A high-level, Pythonic web application framework.
http://pypi.python.org/pypi/Kotti

MediaCore Video CMS
Is an open source media focused content management system.
http://mediacore.com/

Full List:
http://wiki.python.org/moin/ContentManagementSystems

Web Applications

OpenERP
An open source comprehensive suite of business applications.
https://www.openerp.com/en/

GNU Mailman
One of the more popular packages for running email mailing lists.
http://www.gnu.org/software/mailman/

MoinMoin
A wiki engine.
http://moinmo.in

Planet
A feed aggregator.
http://www.planetplanet.org

Plone
An open source content management system.
http://plone.org

Roundup
A bug tracking system.
http://roundup-tracker.org

ViewVC
A web-based interface for browsing CVS and SVN repositories.
http://www.viewvc.org

Trac
Web-based bug/issue tracking database, wiki, and version control front-end.
http://trac.edgewall.org

Full List:
http://en.wikipedia.org/wiki/List_of_Python_software

GUI Frameworks

Tkinter
Python's "standard" GUI library.
http://wiki.python.org/moin/TkInter

PyQT
Python bindings for the Qt application development framework.
http://wiki.python.org/moin/PyQt

WxPython
wxPython is a GUI toolkit for the Python programming language.
http://www.wxpython.org/

PyGTK
A set of Python wrappers for the GTK+ graphical user interface library.
http://pygtk.org/

Full List:
http://wiki.python.org/moin/GuiProgramming