The door on the cabinet where I installed my slide-out shelves has been loose for a few months. Every month or so I tighten the screw on the little door hinge and then within a week — it's loose again. I was grumbling about this to my father one day when he suggested using toothpicks to solve the problem.
It turns out that the screw hole for this hinge was stripped and a little stretched, which is why tightening the screw helped only briefly. Taking my father's advice, I unscrewed the hinge and placed a few pieces of toothpick in the screw hole. As I reinstalled the screw, I could feel that the toothpick pieces were doing their job. Basically the screw is able to grip onto the soft wood of the toothpick pieces, which creates a tight fit that couldn't be achieved in the stretched and stripped hole.
This solution may not last forever — and it definitely wouldn't be ideal for every stripped screw hole (you wouldn't want to do this for a screw being used to hang something on a wall, for instance) — but it has kept the door on my cabinet tight since Christmas, so I'm happy!
Images: Jason Loper