1. Huge market
Travel is not only a huge industry, but also one that has been transformed substantially by the Internet. More and more people search and book travel services online.

2. Long tail content, user generated
Tripadvisor’s content is massive: more than 40 million pages according to Yahoo. Why? Think about every travel objects worldwide, including destinations, hotel, restaurants, activities, and much more. While Tripadvisor needed to create some initial content, most of the content now is created by owners and travelers which keeps costs low.

3. Inbound links
Yahoo counts more than 16 million links. For owners of well rated establishments, Tripadvisor offers badges that show the hotel’s rating which is a valuable stamp of approval for these businesses. Every widget that owners implement on their site links back to Tripadvisor. Tripadvisor also gets great press (and back links) from its “top 10″ rankings it publishes for many categories. While the page rank of a small hotel might not be that great, articles in the Wall Street Journal (PR 8), Chicago Tribune (PR 8), and many other top sites helped Tripadvisor build and sustain its own page rank 8.

4. Monetization
Tripadvisor found a great way to monetize. Instead of becoming a travel agent itself, it allows its user to request prices from one or more travel sites where you can book the travel service. Tripadvisor then gets compensated for every click it generates for these sites.  This has several advantages: First, it keeps the business model simple. Second, it positions Tripadvisor as a partner rather than a competitor to the online travel agencies. Third, it allows Tripadvisor to stay independent and prevents conflicts of interests that could arise if it took commissions from hotels directly. In addition to the CPC links, Tripadvisor also monetizes through traditional display ads and charges owners for premium services.

What did I learn from Tripadvisor:
1. The power of user generated content
2. Badges and rankings are a great way to gather inbound links
3. Partner rather than compete with bigger players in the industry

Don’t get me wrong, I think these sites are extremely helpful. However, after spending two years in business school, I have gotten used to learning from case studies.  After reading and discussing more than 600 of them with my MBA class mates, I am convinced that they taught me much more than the lectures I heard sitting in my undergrad class room. Even more importantly, I am also able to better remember and apply the concepts I learned from cases than from theory.

My goal is therefore, to build up a substantial inventory of SEO case studies. While I intend to study and write up some of the cases myself, I hope I’ll get help from others who are interested in contributing (let me know if you have an exciting SEO case to share).

I hope that this site can become a valuable ressource for people seeking to learn more about SEO by studying successful and unsuccessful examples.