What's your simplest, most useful small, non electronic/electric gadget?

I've just bought a flexible book weight to keep open the pages of large books. I've made a few cooking disasters by pages flapping over and my not noticing I was working from more than one recipe! Hoorah for simple inventions. What's your most useful, simple gadget? Let's make it harder by excluding anything electronic, electrical or computer based!

Parents
  • Mine is a home made thing. A wooden cylinder (about the size of a Sharpie ) with a piece of a hefty darning needle inserted (the eye end removed). The sharp end has been polished just enough so it won't break skin. I made it to open up knots in threads that happen during sewing, embroidery, Dorset Button making, etc. It has many other uses from scoring and making holes in paper/card, retrieving small objects from crevices and grooming threads to be parallel. 

Reply
  • Mine is a home made thing. A wooden cylinder (about the size of a Sharpie ) with a piece of a hefty darning needle inserted (the eye end removed). The sharp end has been polished just enough so it won't break skin. I made it to open up knots in threads that happen during sewing, embroidery, Dorset Button making, etc. It has many other uses from scoring and making holes in paper/card, retrieving small objects from crevices and grooming threads to be parallel. 

Children