I did a quick search on Google, and it seems that most of the supplements are based on HGH. Before buying anything with HGH, you should read
this article on Quackwatch.com. It will tell you the positive and negative effects of HGH therapies.
In the mean time, humor me with this mental exercise: Imagine you were a drug researcher. Imagine that you had developed a drug that would make people grow taller with absolutely no side effects (which these sites all seem to claim).
Would you...
A) Make up your own cheesy website and try to get people to buy your wonderdrug.
Or would you...
B) Put the drug through clinical trials and get it approved to be sold
on the level to anyone looking to grow taller.
Consider that with option A, you might make some pretty good money and help some people, but with option B you would help millions more people to grow tall and make millions or billions for yourself in the process.
These supposed wonder drugs are listed as "supplements" for a reason. It's because they don't cut muster in clinical trials. Simply put, they don't work. You don't see Pfizer or Merck or Bayer claiming they can make people grow.
Stretching is a good thing to do, and drinking milk is probably good. Turning to the internet for a grow-taller pill is definitely not a good idea.