You might enjoy kelp noodles. They have very few calories so you'll need a carb-dense veggie along side it, but it's quite nice in soup or tossed into a stir fry (Nom Nom Paleo has a great stir fry recipe that uses them).
I have used the Gold Mine brand and like it a lot:
Ingredients: water, kelp, sodium alginate.
Nutrition Facts: Serving Size 4oz Servings per container 4 Calories 6 Total Fat 0g (0%) Saturated Fat 0g (0%) Cholesterol 0mg (0%) Sodium 35mg (1%) Total Carbohydrates 1g (0%) Dietary Fiber 1g (4%) Sugars 0g Protein 0g Calcium 15% Iron 4%