I use them to keep change $$ in, or as toy boxes. Hot wheels and little people fit perfectly.
What about you?
I don't use much protein powder these days. Egg whites are better (not Bob's overpriced shit... costco or walmart). But, for the protein powder I do use, I buy from that lardass Dante, and since he ships in poly bags instead of tubs, I use empty tubs to put the protein powder in.