I remember reading about it here in this section, see what a search brings up.
FWIW: I'm not a fan. Sure, if you are suffering from a testosterone I'm not against you using whatever you need to help. But, to play around just to get bigger gains seems stupid to me. From what I remember reading on the subject: the biggest reason men suffer from low testosterone is a Zinc and Magnesium deficiency. So, get some Zinc and Magnesium supplements and see if that helps. Secondly, once you start using some cream or whatever to raise your testosterone levels, your body cuts back its production (shrunken testicles anyone?). I don't know what would happen if you used a cream for years and then stopped using the cream. IOW: It sounds to me like a lifelong commitment. Given how well my marriage has worked out (IE: another lifelong commitment), I'll pass. If that sort of thing sounds good to you, perhaps you should consider Rogaine, Heroin, or at the very least you could marry my wife.
The thread I read here gave a bunch of good information. You'll need to get tested and see what your levels are (something about testosterone, free testosterone, etc...). After that, a competent doctor could make suggestions. If not, you have found one that wants to make money and if that is the case, consider asking him for some oxycontin...