Bar Keeper's Friend works amazingly well and isn't prone to scratch or mar a finish. Others swear olive oil is great at removing streaks, but we're not sure if want to apply this onto our home entertainment and computer components.
HEAVY CLEAN: For big blemishes, use Soft Scrub with something a little more abrasive like a wash cloth to get those wine, oil, and more difficult to remove stains out!
Magic Sponge and similar melamine foam products can work well, but must be used gently and sparingly. We use it for water/liquid stains, but only go with the grain of the metal (many appliances have a brushed finish which has a grain) with very gentle pressure. Wipe clean with a towel and buff gently. We find these melamine sponges a much safer bet than more abrasive cleaning products like AJAX when more serious stains need cleaning.
Got an even better solution that we don't know about? Let us know in the comments!