Advertising. Love it or hate it, it's here to stay. We see ads on TV, we see ads in magazines and newspapers, we see ads on our favorite websites. We see billboards. We hear ads on the radio. We can't escape them. This inundation of advertisements, however, is a marketer's nightmare. How can you target your potential customers without wasting money on people who don't care? When advertising your goods or services, you don't want to spend money where it's not going to be effective, but how can you know where it's being effective?  With so many options -- and so many competing ...