Once growth plates close, you cant grow anymore.
Most of those sites promote HGH (Human Growth Formula). The ingested (pill) form isnt too effective. Injected HGH can be. In adults it can cause slight deformities if you have already stopped growing. IGF-1 is the main cause of this. One guy reported his nasal polips (sp?) growing back afterh aving them removed 2 years later and his ribcage too.
Generally it is the jaw, forehead, and ribcage, which can give a neanderthal look.
My advice. Lift weights, stretch. Build muscle, then stretch it. Do this from age 15 to mid 20s.
I am 6' 2". I dont really care to grow. I have loved milk all my life and always drank it. Soda too... never really ate right. Dad is 6' and mom like 5' 7". In my genes I guess. Hmm.. milk is good.. ramble off..