Of course, there are many different ways to use the Web to advertise and promote products and services. New platforms and new formats are being developed every minute. However, one of the keys to using any marketing or advertising medium effectively is being able to quantify, qualify and measure performance.
Many traditional media companies (Radio, TV, Print) would prefer that you didn't hold them accountable or measure their performance. But, if it's digital, there are ways to measure it. You have a right to evaluate advertising media before, during and after you buy it.
The basic digital (Web-based) ad formats of streaming (computer delivered radio), Web ads (tile/banners on Web sites), E-mail Newsletters (electronic database marketing) and video ads (pre-roll, gateway, etc.) are all measurable and allow for the use of understandable metrics.
A great resource for understanding all of this better is the Internet Ad Bureau. This Web site is very useful: www.iab.net