Geographic point / polygon representation in Python / Django

I am creating a site in Django and I want one of my datatypes to be a geographic polygon. I want to mark points on a map (for example in Google Maps) and then save the resulting polygon to a database. Is there a way to do this that would save me the trouble of manually typing all latitudes and longitudes?

My guess is that I am looking for a geographic library for Python and for a dedicated site that will allow me to plot points on a map and save them in a standard format. Thanks!