Sometimes when we develop a site our main purpose is to sell a product. But tell me why I should ever visit your site again if all it consists of is an online ad for some product, no matter how useful it is. You have to realize that the Internet does not work like the rest of the world . On the Internet people search for information and they love everything that is free.
Free information is one of the greatest novelties of the Internet.
If you are selling a product like spaghetti sauce, then have your site be a site where people can find great recipes. Then in a subtle way let them know that your spaghetti sauce would work best in those recipes. Would you like to see a great example of this. At this site you will find a cookbook, you can sign up for a newsletter, learn some Italian, and more. It is really an entertaining site and the owner is Lipton who owns Ragu'.