The document discusses 7 traits of successful social media applications and opportunities for marketing applications on Facebook. The 7 traits that lead to successful applications are: self-expression and customization, turn-based asynchronous interaction, rewards like scores and levels, ego and status, fresh user-generated content, comparing and sharing content with others, and ensuring applications are fun, cute, and encourage meeting new people. The document also provides 10 steps for engaging users on Facebook applications and 13 points for marketing applications on Facebook, such as through notifications, sharing on the news feed, inviting friends, and interactions within the application.