Jewelbox, just google it. It's quite well known that there ARE products that work and medical doctors know about this.
Alternatively, one can go for a hair transplant, although this is a very costly procedure and only feasible as a solution when enough donor follicles are available.
There's a fair amount of research being done into the cloning of hair follicles for the purpose of transplanting, but success rates are still quite low and it's quite experimental still, so not available to just any man on the street.