Ok, I've been thinking about this so much the past few weeks I couldn't resist sharing it with my favorite community here at SEOmoz...

Up until now, Facebook has been one of those interesting social networking sites that seems as though it should have really great marketing potential, but no one could really figure out how to market anything, let alone monetize. Similar social networking sites like Myspace had seen some success in viral widgets, applications, and third party tools, but have struggled recently amidst restrictions aimed at curbing abuse. Among the most restrictive was an update that disabled external linking from inside flash documents (more about that here), although we found a workaround. For many, this has salted the once fertile marketing opportunities available on Myspace.

Now, with the emergence of the Facebook Developers Platform, there is an opportunity that outshines even that of Myspace in its days before restriction of third party tools, widgets, and applications. The Developers Platform opened at the end of May, and since then more than 1000 programmers and internet entrepreneurs have taken advantage of the development platform to create some incredible new applications for Facebook (and some of them are cashing in BIG TIME).

Perhaps the best success story thus far comes from the application ILIKE (read an interview with the creator here). This application is the most popular on Facebook, with almost 4 million users. The application lets you add music to your profile and find your favorite concerts. It also finds free mp3s that match your tastes and has a few other cool features, including a game. It is an original application that ads value to a profile and that has fun and useful interactivity. Truly an amazing story, right? Yup, but it's not the only one. Almost another 20 applications have over 1 million users, and dozens more have tens to hundreds of thousands. It is quite simply, a feeding frenzy.

The new Facebook developers platform is, in my opinion one of the greatest opportunities we have seen in the past 5 years. Not only does it allow you to build a business on the back of one of the greatest social networking sites in the world, but they allow you to monetize and take ownership of your application as a brand and as a business.

How exactly does one go about monetizing a Facebook app?

Well, there are two principle ways. The most successful will probably use both.

First is through traditional banner/link advertising. Facebook allows for the placement of banner/text ads on the "Canvas Page" of your application. The Canvas Page is essentially the homepage of the application; it is what users see when they sign up for your application. It can also be used as a center for interactivity outside of one's main profile. (This will be more clear if you install an application.)

The second is affiliate marketing. ILIKE uses this ingeniously. Having an application based around music, they feature iTunes links (with their affiliate id) for all of the songs each person has on their profile. Let's do a little math:

(all very rough estimations, but I think we can all agree they are making a lot)

iTunes affiliates earn 5% on all referrals.

iTunes songs cost $0.99 each.

ILIKE makes roughly $0.05 on each song downloaded through their affiliate links.

ILIKE has roughly 4 million users.

Now, let's estimate that each profile gets on average just 2 page views per day.

That's an estimated 8 million ILIKE page views per day.

Lets say they have a pretty crappy conversion rate of 1%. That would mean they have potentially 80,000 conversions per day. Given that each conversion is 5 cents, they are looking at $4,000 a day in iTunes affiliate commissions alone.

All of this is wonderful, but perhaps even more valuable than the affiliate and advertising sales is the fact that they almost instantly brought popularity and brand recognition to ILIKE, including increased popularity to their website ilike.com.

The most exciting part about Facebook opening itself up to developers is the incredible potential for instant viral spread. If your ideas is good enough, built in Facebook features such as "share with friends," "news feeds," groups, mass messaging, and more will make sure it gets out there far and wide, even with the most meager of marketing efforts.

How many of you are going to jump in and take advantage of this amazing opportunity and whip up an awesome application asap?

At Voltier we have done two with some initial success and are about to launch a third.

If you are part of Facebook, check out:

-Our Political Widget

-Our Interactive Movie Application

-Our Interactive Book Application

Anyway, I really wanted to know what everyone else thought of this opportunity, and what you were all doing about it, because to me, the opportunity seems out of this world.

*update: looks like one of the apps that appeared just a few weeks ago was just bought for $60,000. Check out that story here.