According to recent eMarketer research, Facebook is the number one seller of display ads in the US. eMarketer expects Facebook to generate $2.19 billion in display advertising revenue this year.

How much is expected for Yahoo? $1.62 billion.

And what about Google? Only $1.15 billion.

We all know that if we want to place text ads on a website or blog, AdSense is the first place to go for revenue. AdSense is great because it delivers ads based on the website hosting the ad. But AdSense doesn’t seem to really know much, if at all, about the audience viewing the ads.

So what about display ads? And what about targeted, relevant display ads?

Mark ZuckerbergEveryone talks about targeted and relevant advertising, but no one has been able to deliver this in the way that Facebook can within Facebook.com.

It must be only a matter of time before Facebook decides to add advertisements to the Open Graph.

We already see “Like” buttons everywhere and companies like Amazon, CNN, Levi’s and Huffington Post have done some interesting personalization-like implementations on their sites.

Anyone can add a Facebook plugin in a matter of minutes.

So why not Facebook ads all over the web? Why not a FacebookSense of sorts that would allow both large and small sites to deliver targeted and relevant ads to Facebook users?

Think about. You’re connected to Facebook and happen to stroll away from Facebook for 5 minutes and end up on a sports blog. And let’s say you’re a young woman who recently got engaged. Facebook knows you’re engaged and you’re a young woman who likes to run so maybe it would show you a wedding dress ad and a Nike Women Sponsored Story. It might not be perfect because Facebook wouldn’t know whether you’ve bought that wedding dress yet but it would be a better experience than seeing an ad about muscle gain next to an ad for a questionable dating site, right?

And what about visitors who are not on Facebook or don’t feel like connecting to Facebook at that time? Well, Facebook could deliver ads based on the content of the site itself just as Google AdSense does.

My guess is that a Facebook AdSense coming and it’s coming before 2012. Why before 2012? Well, because 2012 is the alleged IPO year. Oh, and also because 2012 might be the end of the world. And Facebook doesn’t have time to wait until the end of the world.