I believe you are talking about Punch Card Incentives (http://www.relayforlife.org/relay/bestpractices). I was also interested in doing this but I cant find any more information. I called our ACS Staff Partner and she said she could try to find it on the LINK or we could use the same concept and make our own. Consider goals such as:
Have each team member complete the ACS CAN
Have certain amount of team members
Have all team and member registration fees paid by certain date
Have every team member complete TeleFriend
...and so on. You can pretty much do anything you want to fit your local needs. We are trying to keep our goals focused on the ACS Mission, fun and achievable. As far as prizes we were thinking:
Reserved parking at the Event
Early campsite setup. (In our Relay campsites are first come first serve and setup doesnt begin until the day of Relay. We will be there the day before setting up for Relay so we are offering as a prize, early setup on the same day we are setting up for the event. This way they get their pick at prime real estate!)
Winning teams are exempt from post event clean up duities
If you have a golf cart at your event, offer to haul winning team's gear to and from their campsite
Again, prizes can be anything you can imagine and dont always have to be a tangible item, they can be a privlidge.

Hope this helps!