Under Django 1.7 and above (thanks Colin Anderson):
from django.apps import apps
apps.get_models()
Under Django 1.6 and below.
If you want all models, try:
from django.db.models import get_models
for model in get_models():
# Do something with your model here
print model.__name__, [x.name for x in model._meta.fields]
I believe the older function still works.