I have managed to make a widget for my website where you select your friends via multi-friend-selector and send them request to join your app, Is it possible in similar way, to send request inviting (suggest) your selected friends to like your Facebook Fan Page?
You not really can send invitation that includes ability to like your page, but nothing stops you from sending invitation to users that may be used in your application (based on some data passed with request) to show explanation engaging users to like your page.