There are a few.
1) For every one hundred dollars you spend you earn a point. Each point is equal to one dollar. To redeem your points you simply have to call or go online and order a card and transfer your points/dollars. Fairly simple but not the best reward plan out there.
2) From time to time there have been offers where you can book special packages from Disney before the offer is open to the general public.
3) You receive a discount off of merchandise from time to time at certain stores.
4) You receive offers for bonus points from time to time as well.
5) Sometimes there are offers for tickets to shows like Disney on Ice, offers for merchandise or collectables and so on.