I have shared this tip many times over the years with buyers and sellers. I am always amazed by how well it works on getting those yellowed spots off white appliances!
Here is the link I found helpful: http://askville.amazon.com/clean-drips-fingerprints-white-kitchen-appliances-cupboards/AnswerViewer.do?requestId=155822
"Sometimes you just need to try something simple... like baking soda. Vinegar,
baking soda, and lemons all have natural cleaning powers that rival manufactured
cleaning solutions. They are easy and safe to use, and can often clean for much
less money than other cleaning products on the market.
Soda Tip: Make a solution of 1/4 cup of baking soda, 1/2 cup of vinegar, and 1
gallon of hot water. This mixture will clean of grease and grime as well as
Baking Soda and Whitening: Mix a quarter cup of baking soda
with a few cups of warm water and wash down the outside of white appliances.
Allow it to stand for 15 minutes before rinsing clean and it will help remove
yellowing of the appliances and restore the whiteness."
Hope this helps!