I posted this in another section and thought I should post it here. if you scroll down they give a lot of info regarding The Top 10 High Protein Foods by Nutrient Density, Other Protein Rich Foods (Especially for Pescatarians and Vegetarians), Low Calorie Snacks High in Protein (50~200 Calories Each), and Protein Isolates. I thought it has some great info using the mathematical breackdowns of some of the foods, or supplements, we are eating, or should be eating. I hope this helps some of you:

http://www.healthaliciousness.com/articles/foods-highest-in-protein.php