Supplements that work?

Is supplement X the best thing since sliced bread? Will amino acid Y allow me to train everyday without a problem?
The answer to these and every other possible question of the sort is a sounding NO. If I had to evaluate all the several factors that come into play to keep us (or help us get) strong, lean with the right weight, properly recovered, ready and willing I'd say it all comes down to Diet, Exercise and Rest.
Supplements should be understood exactly as the meaning you can find in a dictionary: "something that completes or makes an addition" (Merriam-Webster in this case). Supplements should come in when you need extra amounts of something you can't get easily through diet or to make sure you get the nutrients you need when it's just not practical to eat a proper solid meal.
I won't get into supplements that I've fond do not work for me or simply aren't worthy because the list would be extensive. If it's not on the list chances are they're not worth it for me but feel free to ask in the comments.