I've used Nature's Best Zero-Carb "Isopure" protein powder as my late night/evening protein drink. Only about 110 calories per serving, 25g of protein, and ZERO carbs. They also have low carb versions as well. LACTOSE FREE TOO! You only use water to mix. You can get it at any health food store. I buy mine here, I find it the cheapest:
http://www.massnutrition.com/categories.cfm?cur_man=NATURE%27S%20BEST