Facebook has introduced a new feature called “action links” for the Open Graph apps available for Timeline. The new action links are customisable links that allows your friends or those who've subscribed you to do something within your app when your Open Graph stories appear in their news feed, timeline, or ticker.
Facebook explains the new feature an example – when someone checks in on Foursquare and shares it on the social networking site, friends can already like/comment on the post that appears on the news feed. Now, with action links, Foursquare added a “save this place” link, which enables friends to save a place to their foursquare to-do list directly from Facebook. To put in, the action links let you to take a direct action within the app itself.
"Action links tie one action to another, and can be part of any Open Graph story," said Facebook. "Developers can designate an action link for any action they define, which will then appear throughout Facebook." To know more about the new action links, read the documentation on Facebook Developers: Action Links.