Food Substitutions?

I just substituted greek yogurt in place of sour cream in a white chili. Worked wonderfully, dropped the fat and increased the protein.

I have used applesauce in place of oil to make baked goods. I have tried the "banana" ice cream. My favorite summer treat is either a fresh fruit smoothie (in lieu of a milkshake) or chocolate graham crackers with whipped cream (in lieu of ice cream sandwiches.)

What are your favorite food substitutions?