Done with mixing shakes so don't use the above anymore...
Slim-fast makes a 2g carb 20g protein chocolate shake that comes premade in a can. A little high in sodium but otherwise loaded with good stuff. (Look for the "low carb diet" type)
I use it as an occasional meal replacement to keep me on track or a pre-workout protein source. Great to put a few in the fridge at work for those days when you get real busy and can't eat right otherwise, or a mid-afternoon complement to a salad for lunch.