Non-fat, plain (unsweetened) greek yogurt is a marvellous thing. It's good stirred into oatmeal along with mixed berries. You can use it in place of mayo in tuna or chicken salad. Mix berries with it and pop it in the freezer for a couple of hours and it makes a sweet treat with a decadent feel. With some herbs and some fatfree powdered buttermilk, it makes a passable ranch dressing.
It has high protein, too.