Celery together with RabbitMQ (or another message broker) is great for big/huge projects. For basic job queueing and delayed job execution, beanstalkd (http://kr.github.com/beanstalkd/) is in most cases a better choice. It takes almost no memory, no configuration, and just works.

I wrote a small library for Django that makes writing jobs for beanstalkd easier (http://github.com/jonasvp/django-beanstalkd). There's also a management command for starting (threaded) workers. Makes writing and calling jobs from Django very simple.