Ozzy - interesting point there - nature is left handed. Most coiling runners will curl anti clockwise.
On a similar note the sugars produced by plants are all the 'left handed' ones (also known as cis-trans isomerism). For those who don't know what I'm talking about, carbon ring structures in sugars, complex acids and so on can be in one of two shapes - a 'left handed' and a 'right handed' version. Nature almost always produces the left handed version. Interestingly industrially we tend to find it much easier to produce the right handed version. For example, the right handed version of the fructose sugar is the same stuff they use in artificial sweetners.