rq
RQ is a simple Python library for queueing jobs and processing them in the background with workers. It is backed by Redis and it is designed to have a low barrier to entry.
Project Source: https://github.com/nvie/rq
Project Homepage: http://python-rq.org/

luigi
Luigi is a package that helps you build complex pipelines of batch jobs. It handles dependency resolution, workflow management, visualization, handling failures, command line integration, and much more.
Project Source: https://github.com/spotify/luigi
Project Documentation: http://luigi.readthedocs.org/en/latest/api/luigi.html

celery
Task queues are used as a mechanism to distribute work across threads or machines.
Project Source: https://github.com/celery/celery
Project Homepage: http://www.celeryproject.org/

schedule
An in-process scheduler for periodic jobs that uses the builder pattern for configuration.
Project Source: https://github.com/dbader/schedule

pika
Pure Python RabbitMQ/AMQP 0-9-1 client library
Project Source: https://github.com/pika/pika
Project Documentation: http://pika.readthedocs.org/en/0.9.13/

pyres
Resque is a great implementation of a job queue by the people at github.
Project Source: https://github.com/binarydud/pyres

kombu
Kombu is a messaging library for Python.
Project Source: https://github.com/celery/kombu
Project Documentation: http://kombu.readthedocs.org/en/latest/

huey
a little multi-threaded task queue for python
Project Source: a little multi-threaded task queue for python
Project Documentation: http://huey.readthedocs.org/en/latest/