Here is a list that was compiled with the input of everyone who read the original thread and made helpful suggestions. It covers all cruise-related expenses you might have in addition to the cruise fare and gratuities.
1. Alcoholic drinks at the bars and from roving servers (welcome aboard)
2. Wine by the glass or wine packages at meals
3. Spa treatments
4. Shore excursions (including cabanas and rentals at CC)
5. Purchases from the stores: clothing, sundries, jewelry, souvenirs, etc.
6. Adult dining (Palo, Remy)
7. Bottled water
8. Photos (individual and packages)
9. Onboard booking for future cruises
10. DVC membership (you can purchase on board)
11. Art (thank goodness those "auctions" are gone, but you can still purchase art)
12. Candy and snacks outside theater
13. Tips for room service
14. Internet
15. Room upgrades (usually at port, sometimes GS)
16. Bingo
17. Parking/transportation
18. Port porters
19. Alcohol and cigarettes for delivery at end of voyage
20. Welcome aboard packages (flowers, candy, etc waiting in your cabin)
21.
Adventures by Disney (you can purchase on board)
22. Cameras from photo shop
23. Cellular phone calls (although it will be billed later to your phone bill)
24. Medical care
25. Cigars (Meridian bar)
26. Arcade
27. Hair Braiding
28. Nursery
29. Tastings and Mixology
30. Excursion tips
31. Soft drinks from room service or bar
32. Specialty coffee
33. Meeting room rental
34. Onboard or
Castaway Cay wedding (currently $3000/$4000)
35. Vow renewal ceremony
36. Sports simulator
37. Laundry room and send-out laundry and dry cleaning
38. Tuxedo rentals
39. Room service sodas and candy (these have a charge)
40. Additional tip (over the automatic) for bar servers
41. Required gratuity added to spa services (yes, required)
42. Pins sold at trading pin sessions
43. Disney Vacation Club (can be purchased on board)
44. Duties at customs at end of cruise if you've made a LOT of purchases abroad
45. Ship to shore calls from your room phone