What is the supplement Emer'gen-C for? What does it do exactly?

Answer 1

Boosts the immune system.
Or at least that's the reasoning. I don't think there have been any scientific studies done specifically.

Answer 2

Here's the link to go investigate for yourself: http://www.alacer.com/default.asp

I like the idea that is is made of mineral ascorbates (as opposed to ascorbic acid) which is closer to eating food with naturally occuring vitamin C, easier on the stomach, and has some bioflavinoids - quercetin specifically.

This product also has zinc, another valuable immunity booster.