In April of 2004, a small company called Travelzoo (Nasdaq: TZOO) had a number of investors who started pushing a concept - buy shares of TZOO, subscribe to their email travel specials newsletter (give them your email address) and then get as many of your friends and associates as possible to buy the stock and subscribe to the newsletter too. It was a grass roots marketing twist on the old Peter Lynch concept of investing where you shop and shopping where you invest.

Travelzoo's business model was driven by the distribution of travel discounts and specials through email newsletters, so the company was able to charge travel suppliers higher rates when they had more subscribers. The concept apparently worked, as the number of subscribers increased significantly and TZOO reported sequential revenue gains of 11% for the first quarter this movement began (Q2 2004) and then 32% the next quarter (Q3 2004).