I want to know your Best Frugal Idea!

I know with the economy, the best ideas of being resourceful are right in your own home. Anything from growing your own vegetables to saving mason jars to use as drinking glasses. I want to know your best frugal idea! The best one and funniest one I have heard so far is dumping out their vaccuum bag full of dust and dirt and reusing the bag. Maybe not the cleanest but definitely frugal!!