Any uncommon household tips you've discovered?

Most people have seen the 101 uses for baking soda… have you made a serendipitous discovery yourself that saves you time / money / effort / pain? For example, when hammering nails to fix a drawer, I used a small thin book with the binding against the nail to keep it straight without having to worry about hitting my thumb. A string come out of drawstring pants & I tied the end of the string to a long nail & used it to easily snake the string back through.