Can you guess which independent website reached 10 million monthly visitors the fastest ever? No, not Facebook in its infancy, but a new social photo-sharing site called Pinterest. And it represents exactly why I believe investors should avoid the coming Facebook IPO.

Very pinteresting
Users on Pinterest "pin" up photos that they find around the Web to virtual boards, which can be seen and again pinned by other users. The site has proven extremely popular among women, with 82% of users being female, and a vast number of pictures being related to fashion, weddings, kittens, and puppies. And with research showing that women control 85% of household purchases, that's a great demographic for future business.

While Facebook drove over 26% of website traffic, from Pinterest 3.6% referral traffic beat Google's (Nasdaq: GOOG) YouTube at 1.05%, struggling Google+ at 0.22%, and LinkedIn (NYSE: LNKD) at 0.2%. And Pinterest reigns as the top social referrer  at sites oriented toward women, like Martha Stewart Living Omnimedia's (NYSE: MSO) marthastewart.com and marthastewartweddings.com, beating both Twitter and Facebook combined. Martha Stewart's websites now have the "Pin it" button, right next to Facebook's "Like" and Google's "+1."

This shows how quickly sites can go viral, and how little competitive advantage these websites have. Pinterest's rise, like New York Knick Jeremy Lin, is fascinating to behold, but it also reminds us that there is nothing holding back another Pinterest (or Lin) from taking its place.

When a better technology comes along, there is little cost for a consumer to switch – as they did, for example, from Yahoo! to Google around 2003. While Google+ was seen as the biggest threat to Facebook because of Google's size and built-in user base, Pinterest demonstrates that a small player might be what Facebook should fear instead.

The unfriendly business model
Because of its infancy, Pinterest has yet to make money, but through its inherently visual platform where products themselves can be shared, users could browse the site as a marketplace. Add in the female demographic, and it's not a stretch to see how Pinterest could profit.

This is unlike Facebook, where users are not searching for products or services, but instead interacting with one another. Facebook, taking a cue from the newspaper industry, monetized these interactions through targeted ads pasted alongside content. But are targeted ads enough to entice advertisers when sites like Pinterest offer up consumers who are already in the shopping state of mind?

Further, Facebook has failed to identify niches where it can make money other than general time-wasting. LinkedIn fills the professional role and allows you to find employment or employees, while charging for the service. Zynga (Nasdaq: ZNGA) pumps out games to entertain, and recently started a venture to bring into the real world toys and games, all of which can be billed to the consumer. Of course, a small share of Zynga's revenue ends up in Facebook's bank, but Zynga has just announced that it will be launching a new website to access its games, apart from Facebook.

As the trend moves toward more-focused sites like OpenTable (Nasdaq: OPEN), which provides a restaurant reservation platform for both businesses and consumers, Facebook's lack of specialization may leave advertising as its sole business model. And whereas OpenTable earns money from both subscription fees and a cut from reservations, which helped push revenue up 21% last quarter, Facebook relies on its ability to sell its users' information. Even if Facebook becomes the ubiquitous online-identity platform that is used to login to any website, both businesses and consumers do not, and likely will not, pay to use it.

Not a fan
Pinterest represents what any Facebook investor should fear: the future. With no sustainable competitive advantage, and a lack of an enticing future revenue stream, Facebook gets a "dislike" from me -- not even considering how mispriced the stock IPO will be. Sure, 12% of the world's population uses Facebook each month, but none of them pay a dime.

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