Weight gainers put on weight. If its not muscle, its fat. Thats what you mean by weight right?
The best supplement to make your muscles grow really isnt much of a supplement but whey protein. Couple that with a good diet and proper lifting and you will gain muscle.
There is no such thing as an easy way to get muscle so if you are looking for a pill/powder to do that for you.. you're sh*t outta luck.
EDIT: I suppose Creatine could be grouped in with muscle gaining supplements..
