Gangstas are known to carry the €500 note as there currently is no form of currency with more "bang for the buck". If you need to stash large quantities of money in as small and lightweight way as possible the €500 note is the way to go... that's almost $750 in a single bill!
Old article:
http://www.slate.com/id/2111504/
And yes, some of you are arguing that we shouldn't lose the concept of a penny. The trading example is spot on. Some products trade in ranges as tight as half, or even a tenth, of a basis point! A basis point is 1/100th of 1 percent (which is 1/100th of a given value). A tenth of a basis point would be 1/100,000th of a value. So we already trade in amounts way less than a penny and we don't need physical currency to do so. Get rid of the penny!