Everyone should have a good gravy recipe.
The recipe I'm sticking with is my current 2nd favorite recipe from the New Farm Vegetarian Cookbook
You can view the lovely recipe here on someone's flickr page. I love the drawings and illustrations in this cookbook.
This recipe is EASY, and uses ingredients you "should" have in your kitchen at all times anyway.
Toast the flour, stir in nutritional yeast, then oil. Cook until bubbly, then add water, whisking until it thickens and bubbles. Add soy sauce (or Bragg's liquid aminos) and salt and pepper to taste.