I agree with all of them - extra boxes and frames all the time, and a nuc box. I have a little "hive kit" that I keep next to the hives. It's just a large plastic box (bought at walmart) that I keep my tools in. I've got two hive tools, my smoker, some cotton, a couple bbq lighters, some cardboard, bee brush, and a few extra frames in there. I also keep an extra box down at the hives (no frames) just in case I need it to hold frames. It usually sits on top of a screened stand that has no exit on the bottom. It has worked great ..... and here's what I often use it for: I put the box on the stand, and place the hive lid next to it. As I pull out frames of honey, I'll get the bees off them and place them in this box. I then put the lid on it, and since the bottom has no way in, it secure from bees returning to the frames. Then I can move on to the next honey frame doing the same with each.
Beth