My wife and I spend a lot of time online. The other day, I lent her my notebook for a few minutes mid-surf, and she quickly went over to Reddit. As it turns out, most of the links I’d opened were the ones she wanted to read anyway. Over at GigaOm, Om’s been reflecting on Facebook for some time now. And this got me thinking.

Surfing is increasingly a social activity. Think of news aggregators as questionnaires: “Which of these stories do you find most interesting?” If we are what we surf, then the people with whom we have the most in common are likely to have similar surfing patterns. This notion alone isn’t particularly revolutionary, and it’s driving innovation in fields like web analytics. But apply it to Facebook Connect, and it opens up a whole new realm of social networking.

Online dating uses similar models. Sites like eHarmony get members to fill out lengthy personality tests, which they then use to find prospective dates. But tastes change, and surveys are time-consuming. And lack of membership is making it hard for the industry (which started off strong at $300M in 2002 but is plagued by anemic growth — 4.5% a year across 850 sites — and frustration with inaccurate profiles.)

Facebook, on the other hand, has it easy. Because it will know what links I follow, what books I look at, and what videos I watch, Facebook may soon be better at finding a match than match.com.

• It’s easier: I never have to fill in a form.
• It’s up to date: It adapts as my tastes change.
• And there are more fish in the sea: With Facebook behind it, there would be a vastly bigger user base of mates from which to choose
• Introductions are a snap: The system knows how to let me reach them, Linkedin-style.

Of course, letting other people see what you surf can be creepy. Facebook’s first attempt at this, Beacon, stumbled famously (so much so that at least one smart VC confided in me suspicions that Beacon intentionally overstepped its bounds so subsequent, less draconian, models would be welcomed.)

But consumers are now much more comfortable with sharing online activity, and Facebook is uniquely positioned to blend that activity with its social graph. Dating’s just one example. Consider social engineering and “friend spam.” Facebook could quickly determine which of your online friends are truly your friends, and which are likely to be solicitations from strangers. That’s critical for trust-related industries like security.

As we learn more about Facebook Connect, we’re likely to see a wave of new applications, from dating to spam protection, that will greatly expand the utility of Facebook’s platform.

It may even make the company some money.