How about having a SingletonModel in Django?
Try django-solo, it works in django 1.5 + for sure, django-singletons doesn't work with 1.5 + because it uses a deprecated feature.
I think having a "singleton" model is ugly; it's dumb use of the relational database and it's bad UI, because the admin UI is built around working with lists of objects.
Instead I prefer to use a generic solution like django-chunks or django-flatblocks for this.