Because this gets asked so often I've compiled a list of things to spend OBC on. The only thing I know of now that you CAN'T buy with OBC is a deposit on a Future Cruise. You need a credit card for that. Also, there may be some card game in the casino with a cash only buy-in. And if they do a fundraiser, like selling t-shirts to “save the reefs” and the like, expect to need cash for that. Otherwise, here you go:
*Acupuncture
*Airport transfers
*Alcove Rental (some ships)
*Apple products etc. and Ilounge classes
*Art Auction Purchases
*Babysitting
*Barber Shop services
*Behind the Scenes Tours
*Beverages -- Alcoholic, carbonated soft drinks, specialty coffees and teas, bottled water — if not in your package, also beverages above your package limits
*Bingo and Deal or No Deal
*Bottles of wine
*Casino
*Chef’s Table
*Corkage charged if you bring your own bottles of wine to the MDR
*Duty free liquor and cigarettes
*Extra cost entrees and other items in Main Dining Room and specialty restaurants
*Extend Your Stay program
*Fitness classes
*Flowers
*Gelato
*Gift shop souvenirs, purses, watches, cosmetics, clothing, jewelry, etc.
*Gratuities, and extra gratuities
*Guests dining with you in Luminae (applies to Suite Passengers only)
*Guest entertainers' CD's and DVD's
*Hair and nail salon
*Hollywood hot glass experiences (some ships)
*Internet if not in your package, also Internet upcharges
*Laundry/pressing/drycleaning
*Liquor Tasting events
*Luggage Valet
*Martini Flights
*Medical Center purchases
*Mini bar
*Portrait photo sessions
*Pay-per-view movies
*Persian Gardens passes
*Personal Training Sessions
*Photos & cameras
*Room service fees
*Ryde spinning classes
*Shore Excursions
*Shuttle to town (some ports)
*Spa -- massages and treatments
*Specialty restaurants
*Teeth Whitening
*Telephone calls using ship's system
*Transfer to another passenger's account
*Voyage in Review DVD
*Wine and liquor tastings
*Zumba
They will always use non-refundable OBC first, then refundable OBC, And if you run out of that then it goes on your credit card