When I first started out with Python / Django it quickly became apparent that there are a ton of open source packages out there. Here’s a rundown of some of the ones I’ve found to be most helpful so far…
Python interface to Amazon Web Services.
Useful extensions for the Django framework.
Utilities for implementing a modified pre-order traversal tree.
A Django field for custom model ordering.
Helping you remember to do the stupid little things to improve your Django site’s security.
A collection of custom storage backends for Django.
A fully tested, abstract interface to creating OAuth clients and servers.
A Python-based API for communicating with the memcached distributed memory object cache daemon.
pytz brings the Olson tz database into Python.
simplejson is a simple, fast, extensible JSON encoder/decoder for Python.
Intelligent schema and data migrations for Django projects.
Twitter for Python!
Werkzeug is a WSGI utility library for Python.
Command-line tool for querying PyPI and Python packages installed on your system.
I’ll try to keep this list updated as I find more. Please add any must haves in the comments.