Did you know you can use peroxide to whiten your teeth? I read about it in Countryside magazine, and told my DH, because he's always been self-consious about his teeth being yellowed (the result of living with two smoking parents for 21 years).
He tried it, and his teeth are SO lovely and white now! It's very simple, just hold a bit of peroxide in your mouth for a few minutes (5 or so) every morning. I use the cap to measure into, he just pours some in his mouth...just use the amount you're comfortable with in your mouth, hold it there for a few minutes, then spit. Consistency is key...it takes a couple weeks before you'll notice a difference. But it does work, and it's LOTS cheper than professional whitenings or even the store kits...healthier, too.