By definition, a super acid is any acid with is greater in strength than sulfuric acid.  Because sulfuric acid, at least the first proton, is essentially 100% ionized in water, different solvents such as acetic acid are used in order to differentiate the acid strength and show that an acid is stronger than sulfuric.  Perchloric acid is the most common super acid that most people in a laboratory setting will run across.  These acids will also protonate sulfuric acid, forcing it to act as a base:

HClO_4(l) + H₂SO_4(l) <-(H₂SO₄)-> ClO₄^-_(H2SO4) + H₃SO₄⁺_(H2SO4)

Perchloric acid is what I tend to call a simple super acid since it just donates a proton and does not undergo any of the real Lewis acid chemistry most people associate with a super acid.  Many of the Lewis type super acids contain fluorine and involve Lewis acid/base type reactions to yield naked hydrogen cations which and protonate even alkanes. 

All in all they are incredibly corrosive.  Perchloric and hydroiodic acids are super acids and work just like normal acids that people are used to.  They will dissolve metals just as readily.  With regards to consumption in our food, no, they are not intentionally put into our food.

(1) Overton, Tina.  Rayner-Canham, Geoff. Descriptive Inorganic Chemistry.  3^rd ed. 2002 New York:  W. H. Freeman and Company