A few minutes of searching this board will show you more than you ever wanted to know, but here's the quick and dirty answer:
Included in the price of the cruise:
-All meals in dining rooms (including non-alcoholic beverages)
-All room service (24 hours! except beverages)
-24-hour access to the beverage station on deck 9 (coke products, coffee, tea, cocoa)
-All pool deck restaurants (quick service type foods)
Here's what you will pay for:
-alcohol (all locations)
-drinks at the coffee bar near the adult pool (oddly enough, the snacks there are free????)
-stuff from the snack bars outside the theatres (go to the pool deck for free snacks and take them with you)
-Palo (super cheap for what you get. I think the $$ goes for the gratuity for the wait staff - totally worth it!)
-Beverages from room service (we ordered snacks from room service and I sent my DH up to deck 9 to grab cokes while I waited for the food to arrive

)
I hope that helps!
Have a great trip!
--H