Viral marketing

I have recently been looking further into the ideas of viral marketing.  Most definitions of viral marketing agree that:

Viral marketing is:

Definition

Marketing phenomenon that facilitates and encourages people to pass along a marketing message.

Information

Viral marketing depends on a high pass-along rate from person to person. If a large percentage of recipients forward something to a large number of friends, the overall growth snowballs very quickly. If the pass-along numbers get too low, the overall growth quickly fizzles.

At the height of B2C it seemed as if every startup had a viral component to its strategy, or at least claimed to have one. However, relatively few marketing viruses achieve success on a scale similar to Hotmail, widely cited as the first example of viral marketing.

Quoted from http://www.marketingterms.com/dictionary/viral_marketing/

The Classic Hotmail.com Example

The classic example of viral marketing is Hotmail.com, one of the first free Web-based e-mail services. The strategy is simple:

1.   Give away free e-mail addresses and services,

2.   Attach a simple tag at the bottom of every free message sent out: "Get your private, free email at http://www.hotmail.com" and,

3.   Then stand back while people e-mail to their own network of friends and associates,

4.   Who see the message,

5.   Sign up for their own free e-mail service, and then

6.   Propel the message still wider to their own ever-increasing circles of friends and associates.

Like tiny waves spreading ever farther from a single pebble dropped into a pond, a carefully designed viral marketing strategy ripples outward extremely rapidly.

Quoted from http://www.howipromotemywebsite.com/viral-marketing.html

I tried a ‘viral marketing’ software to encourage further traffic to sites, the jury is still out on this.  Yes the traffic increased by at least 1000 visitors on a daily basis but the way the traffic was encouraged to the sites was not necessarily beneficial.  Previously I have always used Twitter and other social networking sites such as Facebook or LinkedIn with keyword postings to encourage targeted traffic.  Numbers have grown month on month; the viral marketing saw a large jump in traffic but no more interest than that generated by seo and social network.  I am coming to the conclusion that ultimately this is all simply a numbers game no matter if your traffic is targeted or simply encouraged it is merely a matter of numbers the more traffic you have the greater the chance of take up of your ideas or goods. Perhaps I am being cynical.  The constant use of annoying pop ups definitely brought more traffic to the sites and this is a tactic shown by many internet marketers, they seem to make a profit from doing these things yet every ounce of my being says this is wrong and is not the way to encourage followers, perhaps I show I naivety that the marketers exploit in me and others, there are many quotes I can think of for this analogy.  These tactics work even though they seem offensive in the extreme, there must be a psychology example of why this behaviour encourages interest yet for so many it offends  perhaps this is a topic to be considered in further articles.  

If you use viral marketing how do you find it?  Does it work for you or do you have as many complaints as followers generated by the viral software? If viral marketing works for you which software/tactic would you recommend?