The top 50 US websites are getting more traffic from abroad than from within their own borders, yet few are willing or prepared to tap into that market, AdAge reports.

Traditionally, US marketers haven’t had much interest in foreign audiences. But today there are more online and media players with an international reach, including Facebook, News Corp.’s MySpace, and Viacom, with its MTV and VH1 online properties.

Search, social networking, and video sites are the domains with the most allure. Google’s performance-based ad model, for instance, derives 50% of its revenue from outside the US, and 84% of all of all traffic to Google sites originates from international sources.