The best and most common uses of it I've found so far is finding recipes. GPT 3.5 is good at it but you generally need to find an actual recipe once you get an idea from it but GPT4 does a much better job of giving you a coherent recipe from the start (trust but verify though).

I give it some restrictions and a few preferences and ask it to suggest 20 things for me to cook. It's very helpful.