Amino Acids have a variety of different health benefits. Each amino acid has a specific function in the body and can usually be found individually, in an amino acid complex like Amino Fuel, or in good old fashioned protein from your shakes and/or meat, fish etc. For the purposes of most at AM, amino acids are the building blocks for muscle, and are in high demand after "ripping" your muscles during intense training (especially glutamine and the BCAA's)
But, for the other health benefits, here's a uick hitlist of some benefits of individual amino acids:
Glutamine - Aids with soreness and muscle fatigue, most widely used amino acid in the body.
Branched Chains (Leucine) - Aids in protein synthesis, and prevents muscle breakdown (catabolism).
Arginine - Precursor to Nitric Oxide, the blood vessel expander. Also aids in cardiovascular health and reproductive health.
Carnitine - Breaks down long-chain fatty-acids and aids in lipolysis, useful as non-stimulant fat burner.
Those are just some of the most important and widely used.