Broccoli is most definitely a healthy addition to a low-carb diet. While it contains only 2 grams of net carbs (not to mention 1 gram of fiber and a mere 15 calories), the good far outweighs the bad. You can look to this veggie to provide potassium, manganese, plenty of folate and Vitamins C, K, and A.
Not only is broccoli very healthy for these reasons, but it has also been shown to have anti-cancer properties, perhaps due to the high levels of antioxidants. Another bonus to this vegetable is the many ways it can be prepared. You can steam it, boil it, bake it, sautee it in oil, or (for the most nutrition) eat it raw. Try it with a touch of your favorite dressing or, for a great low-carb treat, as a salad with bacon, onion, and your whichever other favorite low-carb goodies you want to add in.