In our discussion of cast iron cleaning, we mentioned that you can rub rust away using a raw potato. This tip is so unusual, yet handy (and non-toxic!), that we thought it deserved its own spotlight. And the potato trick isn't limited to cast iron – you can use it to remove rust from baking pans, knives, and other household tools.
To clean rust with a potato, cut it in half lengthwise or crosswise, depending on how large a surface area you want. Dip the cut end in dish soap or baking soda and firmly rub it over the rusted area. If the end of the potato gets slick, slice it off and apply more soap or abrasive. Repeat until rust is removed, rinse, and dry.
Apparently this works because the oxalic acid in the potato helps to dissolve rust. Have you tried this or any other good rust removal techniques?
Related: How To Clean a Cast Iron Skillet
(Image: Emily Ho)
How to Make Easy 3-Ingredient Energy Bars at Home
How To Make Classic Chicken Salad
Good Food to Share 
The Big Book of Small, Cool Spaces 
Apartment Therapy Presents 
The Eight-Step Home Cure 
Elizabeth Apron fro...
Before & After: Emily Henderson Transforms a Senior's Studio Space
Monica & Austin's Charming Bungalow
Totally using this on my rusty knives tonight!
VINEGAR....
Vinegar is a great rust remover. Easy to use and non-toxic. I keep a jar of vinegar just for rust removal. Cover the rusty item with vinegar in a bowl, shallow pan or a jar etc. and let it sit for a while. Could be an hour to overnight. The length of time depends on how rusty it is. Rub/rinse and the rust comes right off. Save the vinegar for the next rusty item.
Brilliant! Filing this trick away for later use.
Potatoes have almost no oxalic acid in them. There has to be a better option if thats really why the method works, though I imagine making a parsley scrub probably is more effort than it is worth.
http://www.nal.usda.gov/fnic/foodcomp/Data/Other/oxalic.html
If rust is your problem then Naval Jelly is your solution, it's cheap and effective.
The potato is just a carrier for the baking soda (or salt, which you can also use) and it's the abrasive action of that stuff that works. It's not the "oxalic acid".
http://www.ehow.com/how-does_4728434_potato-remove-rust-pots-pans.html
@Palmetto - then why doesn't baking soda and a dish scrubby work very well?
I have a cast iron skillet that is seriously rusty. We took sandpaper to it and got most of the rust off, but I'm going to try the potato next! :)