I've used the caloriecount one above, but it seemed like it often didn't recognize what I was entering. So now I use
SparkRecipes. You select your ingredients from a list, tell it how many servings and it spits out the numbers. Sometimes it doesn't have an exact ingredient but in general I have found it to be REALLY useful!
I think if you are a member you can save your recipes, but I'm not a member.