Slice an onion, and blend it into a paste. Mix it with a little water and use it as a metal cleaner. Just rub the paste on with a soft cloth until the metal is shiny and then rinse it with clean water.
A raw onion will also remove rust off a knife. Just slice thru the onion several times until the rust is removed.
Clean your barbecue grill with half an onion. Once the grill is turned on, put an onion on the end of a long fork and move it back and forth over the grill until it's clean.
Painting or varnishing? Use onions to get rid of that strong smell. Just place slices of onions in a bowl of water. Put it in the room that you've painted or varished overnight and the smell should lessen significantly by morning!
For insect bites - rub an onion on it! Onions have an anti-inflammatory effect, so it should help with itching and swelling.
And my grandmothers favorite - if you have a burn, try an onion and water paste. It will help sooth the burn and help prevent infections.
No need to keep those old onions sitting around - put them to work! I'm Mrs. Fixit and it's just that simple!