I really enjoy and swear by "body building style" protein shakes and meal replacements for a low carb diet. Myoplex makes and allready mixed low carb shake with around 4-6 carbs and tastes very good. Universal Nutrition makes a few no/lo carb mixes and Biotest has a zero carb mix which is my fave in the taste dept. GNC is good if you use their discount card and get sale items otherwise try Netrition.com for the best products and prices. They seem expensive but they last a while and are cheaper than a whole meal. I've never used Atkins or any of the other "low carb lifestyle" shakes, I just don't trust them or their bars. Also, it's always a good idea to stay away from soy protein.

I find shakes to be a fast and easy way to stay on my low carb diet because I'm busy and I really don't get too hungry and usually have to force myself to eat.