Facebook Activity Tracker Application

We are a marketing company wanting to create a rewards program to encourage our fans to promote our clients. This would be through wall post comments, suggest to friends function and sharing or re-posting certain announcements. We need a Facebook application that can keep track of these activities. We will assign points based upon these these activities. We will have to come up with a system to determine relative value of each activity. For example suggesting to friends will be worth more than reposting an event. There would also have to be built in parameters that limit actions. We dont want people to spam just to rack up points, perhaps they can only make up to 4 actions a day. The app would need to keep track of rewards earned which they can trade for gift certificates, movie tickets etc. The interface would need to allow us to change values, and limits as necessary. Any other specifics that an experienced designer could suggest would be considered. Links to any similar type app would help.