I do 4 cups of stock (I use Massel powdered stock) and add a box of frozen spinach. Let that boil together first, then add your polenta and stir like mad.
OR - do 3 cups of stock, then pour it into a baking dish and top with some ground pine nuts and garlic. Or parmesan, if you're cheesy.
OR - my other fave - add lemon myrtle to your stock, then serve it with lemon and garlic marinated baked field mushrooms.