I've had good luck w/Twin Labs. I found their sports drinks to be effective for my running and triathlon training. I used them when bicycling as well and they were great. I am using their creatine now (post workout) and it seems to help. I am also using their Tribulus Fuel and noticed a little difference. My libido did increase a little. I didn't use it for size gains or added strength-I wanted to see if it would increase my libido and help naturally boost my test levels. I got overtrained and could tell my test level was way way off-I didn't want to nail the GF, I didn't want to beat it, I was like a castrated dog.
Probably too much info.
Anyway it seems like good stuff.
FHG