Since I have been drinking a tons of green tea, I have found its starting to stain my teeth. (I'm a tea  addict..what can I say)
 I use the usual tooth whitener tooth paste, and I have them polished at the dentist. But they embarrassingly go back to their horrible colour.
Now I have used a lot of whiteners that "claim" they will make my teeth pearly white, you know the ones with the trays that make you dribble like some mad person with rabies.
 
Then I saw these Crest strips, being a bit dubious it took some time before I parted with my cash. I purchased some on Ebay (the premium ones), and tried them out as soon as they hit my doormat.
 
I have to say these are absolutely wonderful, ..after the 2nd day of trying, my teeth were starting to look whiter. You get 2 lots of strips, 14 for the tops and 14 for the bottom teeth. 
You have to careful when you peel the gel strip off, if you get distracted the thing tends to stick to everything else. Also if you have sores on your gums, or cuts I would advise for you not to use them.  Lets just say, I had a cut on my finger and a bit of the gel got in it...it stung like crazy.
I also have sensitive teeth, and these strips are perfectly fine. I have had no side effects when using this product. Its not advisable to try and answer the phone when you have the bottom strip on, other wise you end up sounding like Janet Street Porter!
 
I would certainly recommend these to all out there who have stained teeth, who want that dazzling smile..and not have to pay wads of cash on getting them done professionally.
 
(Oh and a litte plug for someone ) The best place on Ebay to get these...  Chemist-4-u