After waiting for years to have my teeth whitened, I finally shelled out $500 and went to BriteSmile. They offer a special technique that whitens your teeth in 1 hour without any take-home follow up.
The "spa" is nothing special... dental chairs with little TVs that come down over your head. There's no soothing music or fountains like you'd expect in the spa-like atmosphere they advertise, and the staff was not especially professional or friendly.
The process is simple: they paint a solution on your teeth, which is activated by a special light they shine on your mouth. You sit there for an hour watching your little TV, and at the end your teeth are whiter.
My before and after pictures do show that my teeth were lightened 12 shades (which the staff claimed was amazing), but I don't see that much of a difference. In a year or so I will try Zoom Bleaching and see if I can get better results.