I sympathize with your problem of needing protein w/o additional fat. I'm on a 33% carb, 20% fat, 47% protein diet imposed by my internest. Most of my good suggestions have already been mentioned: fat free cottage cheese, light poultry baked or broiled w/o skin, fish, egg whites, fat free skim milk, protein shakes.
I have found American Whey protein shake mix to be the most palatable to me. I have protein shakes 2-3 times a day and still enjoy them. The downside is that you are getting lots of protein and amino acids but none of the necessary vitamins and minerals. I would not recommend 2-3 shakes a day for a normal person. My daughter and her DH work out regularly and have a protein shake after they work out. I have also read that potassium is good for helping build muscles so you might consider adding banana (high in carbs but good for potassium) or kiwi.
I am looking for any kind of a low fat, low carb protein drink that can be heated to make a hot broth or hot chocolate substitute. I have been searching for this for 2 years w/o success so I doubt it exists, but I am hoping somebody on here has some ideas.
I've also found a Greek Yogurt, Fage, that is very low in carbs, fat free and high in protein which makes an acceptable substitute for sour cream or even regular yogurt.