Jewellery cleaner works great for restoring luster to your precious-metal accessories, and it can even take that awful, funky metal-gone-bad smell off of not-quite-precious objects. But paying for the stuff is surrendering to huge markup. Over at RecipeZaar, one helpful user posts a recipe for homemade jewellery cleaner, using salt, baking soda, dish detergent, water, and aluminium foil. It's similar to DIY silver polish, but it's a bit more portable and multi-purpose. Having tried it out on a cheap doorknob that was leaving a bad smell on hands, I can testify it works for that purpose as well.