Non-Food Uses for Cornstarch and Baking Powder

I don't cook an awful lot and because of this, I buy the small sized items when it comes to ingredients needed when I cook. Even when I do buy small, I always seemed to have opened ingredients in the back of the cupboard, for who knows how long. Today my search is on for non-food uses for corn starch and baking powder.

From talking to the county extension office, an opened container of cornstarch, if sealed well and in a dry climate, can last indefinitely. However an opened container of baking powder in the same climate has a shelf life up to 18 months, but you can test it, "Regardless of the expiration date, the effectiveness can be tested by placing a teaspoon of the powder into a small container of water. If it fizzes energetically, it's still active and usable"

Cornstarch:

✜ Burn relief - If it is still around the house when summer rolls in. Mix cornstarch and water until a paste is made. Apply directly to sun burn and allow to dry, then remove with lukewarm water.
✜ Knot detangler - I've heard of baby powder being used and corn starch has a similar consistency. I tried it on my own necklace and it worked very well.
✜ Carpet deodorizer - Sprinkle on carpet, wait 20-30 minutes and vacuum up. I tried this and then steam cleaned and was happy with the smell test result and the dark spots on the carpet cleared up better.
✜ Perspiration Sponge - Pour into shoes or socks or dab some in those special places after your shower. A natural alternative to deodorants, mix 1 part baking soda with 6 parts cornstarch.
✜ Dry Shampoo - Sprinkle on pet or human hair and brush out. Not a fan of this idea, tried this in the past and just had a mess, but some people think it is worthwhile.
✜ Spray Starch - Handy in an emergency when ironing - using a mix of one tablespoon of corn starch and two cups of cold water in a spray bottle, mix well and mist onto shirt collars and pants.
There are other uses for face painting, cleaning silver and killing cockroaches that you can check out.

Baking Powder has baking SODA in it and they both are used for baking. You can substitute baking POWDER in place of baking SODA (you'll need more baking powder and it may affect the taste), but you can't use baking soda when a recipe calls for baking powder. You can find the chemical differences explained here.

Baking Powder: 
✤ Detergent booster - Sprinkle some baking powder into the washing machine or dishwasher with the detergent to boost the cleaning power. And though I'm no Tool Time Tim, I like a little boost here and there.
✤ Counter cleaner - Dust your counter-top with powder and wipe clean for a more natural cleaner in the kitchen.
✤ Teeth Whitening - Small cup of powder and dip your brush in it, then brush for 1-2 minutes while it foams up. Rinse your mouth out well afterwards. (see Dental assistant video)
✤ Grease Killer -  Sprinkle a little baking powder on the greasy spot, shake off extra powder and brush off the rest once the grease is soaked up by the powder. Wash as usual.

It was hard finding uses that specifically speak about baking POWDER, as many got it mixed up with baking SODA, the much cheaper and less acidic version that you usually see in the orange arm and hammer box.

Any additional non-food uses for baking powder or cornstarch that you have found useful?