Your viral marketing.

Viral marketing, the concept of making each customer a marketer by encouraging word-of-mouth referrals, is indisputably one of the most effective mediums of ongoing self-promotion a site can employ. It gives Internet companies a cost-efficient, proven tool to increase traffic and lower advertising costs.
Your potential customers now have the power to tell colleagues, friends and family about great web site experiences in greater numbers and far faster than we could have imagined just a few years ago. Think of the power of a dense email address book and a few mouse clicks. In fact, that is the “fuel” behind viral marketing. The downside is they can do the same thing regarding bad experiences with the same efficiency and speed. Research has shown that people share bad experiences up to 5 times more often than they tell about good ones. Before you post a site to your server and invite people to visit it, everything should be quality tested and in perfect order. While software makers can sometimes get away with shipping buggy software, you can’t issue a “patch” to a site that has already turned off your target audience because in this market, your audience will go somewhere else, fast. And instead of gaining customers “geometrically”, you’ll be losing them exponentially.
There are two basic tools in your viral marketing arsenal: buttons and links. The idea is that with a single click a visitor can share your site with others, and those people in turn can do the same. The goal in designing and placing these buttons and links is to make them obvious, easy-to-use, and perhaps even rewarding to use. By making your buttons more obvious, you give the visitor a visual cue to pass your site on to a friend and take an active role in the creation of your own viral marketing campaign. You can take an even more active role and move beyond mere suggestion by actually offering your visitors an incentive to pass something on.
Button: Eye-catching, can be graphical. Link: Line of blue text. Both viable, both serve their respective purpose. The tool you choose will depend on two factors: 1) what you want your visitor to share with others, and 2) the context in which your visitor will be sharing. If you want people to share content items such as articles or white papers, you can use either a button or a link, although a button is more appropriate as it’s more attention getting. Also, if the context is your site as a whole or a specific product or a service on your site, then a button is preferable because eye-catching buttons can be designed and placed by using simple code that will load almost regardless of browser or bandwidth. However, when the context is email, whether mailing to your own opt-in list, doing a targeted promotion, or simply sending “Thank you” emails when customers submit an order, you are better off sticking with a link. Many of your potential customers don’t have email that supports HTML, and even if they do, a button can easily get chewed to bits in cyberspace when moving across platforms and programs. A good rule of thumb is site = button and email = link.