Since we're on a roll here, let's talk about brass and aluminum.
Brass is a pretty sturdy metal, and it's easy to care for. You can use the lemon and salt method described for copper. It works just as well for brass. You can also use toothpaste. Just rub it on with a cloth or a brush, rinse it off and wipe dry. You can also make a vinegar paste: Mix equal parts of flour and salt. Delicious - not! Add enough vinegar to make a paste. Rub it on the brass with a damp cloth. Rinse and wipe dry. This one also works for copper.
Once you've got your brass looking great, give it a coat of paste wax to retard tarnish.
The British call it aluminium. Go figure. Try cleaning small aluminum objects with ketchup. Just smear it on there, wait a half hour or so, wipe it off, rinse and dry. For larger objects, although you could also use ketchup for them, a nice big can of tomatoes is easier and less expensive. Just submerge the aluminum object in the can and leave it there for the requisite half hour. Rinse and dry. AND DON'T EAT THE TOMATOES!!!! I know I didn't have to tell you that, but it pays to be careful, no?