Do, do, do, do.

It took me a number of years in the business to figure out advertising. After reading all the books, years of practice, and lots of scar tissue from practitioners good and bad, I realized one simple rule: there’s showing and there’s telling. Showing works best.
If you look at advertising that is demonstrating a value proposition rather than explaining a value proposition you are more likely to buy.
Along came the Web and Web 2.0 which have added another component to selling: doing.  You can’t always “do” on the Internet, certainly not in terms of ingesting consumables or trying on clothes, but smart web marketers are finding ways to get customers and prospects to do something with their products. I can’t get you to try on a new style of sunglasses, but I can get you to play with them, put them on an avatar, change the colors. Do, in other words.
In my business, social computing, it’s even easier to get people to do. Of course, I can tell them, Zude is the “fastest, easiest away to build and manage a website,” and I can show them the same in a flash demo, but until I let them put their hands on the controls and do (in consumer marketing this is called sampling) they aren’t really sold.
Prior to the Web, “doing” was always the domain of promotion not advertising. Not anymore.