In this tutorial, Ben Hunt, describes various common graphic design elements in modern web ("2.0") design style.
He then attempt to explain why they work (i.e. why they have become common), as well as how, when and where you might use each element in your designs.
It follows on from his Current Style article, and analyses in greater depth the design features of the current "Web 2.0" design style.
Read Ben's design guide here.