The Worlds Easiest Metal Polish made by Satin Gloss.
Google it, I swear it's the best polish I've ever used (and I have used tons). Works on stainless, aluminum, chrome, ... hell, it works on everything!
When I bought my cam locker toolbox (aluminum diamond plate), I bought a bottle and have been hooked since. Only problem is that nowhere sells it that I know of and you have to order it online.