Consider the following models and form:

class Pizza(models.Model):
    name = models.CharField(max_length=50)

class Topping(models.Model):
    name = models.CharField(max_length=50)
    ison = models.ManyToManyField(Pizza, blank=True)

class ToppingForm(forms.ModelForm):
    class Meta:
        model = Topping

When you view the ToppingForm it lets you choose what pizzas the toppings go on and everything is just dandy.

My questions is: How do I define a ModelForm for Pizza that lets me take advantage of the Many-to-Many relationship between Pizza and Topping and lets me choose what Toppings go on the Pizza?