Great idea & execution! Any reason why you chose to post a "link" to the user's wall instead of something else? I've had more success (higher CTR to app and higher engagement on FB) from posting nice large graphics to a user's wall using the photos API. Make a POST to /USER_ID/photos.<p>Also, I haven't had much success using Facebook invites/requests or the Facebook App Center yet - would be interested to see what kind of conversion you can get.