Pump up the volume by placing your iPhone/iPod in a bowl - the concave shape amplifies the sound.
While travelling, keep shoes in hotel shower caps to stop dirty soles from rubbing on your clothes.
Find tiny lost items like earring backs by putting a stocking over the vacuum hose.
Rub a walnut on your furniture to hid any dings and scrapes.
Store sheet sets in their matching pillow case to keep your linen closet tidy and organized.
What are the others you've seen and thought, "genius!"
Now just to remember them all....