My favourite multi-purpose small plastic box!
I carry firewood in it and empty the wood on arrival at camping. I then use it as a coffee table for the rest of the weekend. At dinner time, I use it as a stable table and eat off it. I later take it to bed with me and use it as a bedside table. It makes it so easy to find all my bits and pieces in the dark if I need. Occasionally I watch a movie on my laptop and it is fabulous place to place the laptop. It also stops ground moisture reaching things, especially the laptop. I then pack all my rubbish in it and take it home with me.