1. Get a haircut
2. Add a beard
3. Get a tattoo
4. Buy new clothes
5. Rob a store
6. Find treasure underwater
7. Visit the fairground
8. Get your car towed and pay a fine to get it back
9. Play Tennis
10. Play Golf
11. Arms trafficking (Land)
12. Arms trafficking (Air)
13. Get thrown out of the strip club
14. Ride the cable cart
15. Arms trafficking (Land)
16. Arms trafficking (Air)
17. Buy and sell stock
18. Buy masks
19. Talk to pedestrians
20. Walk Chop the dog
21. Go to the strip club
22. Hangout with friends
23. Random events
24. Strangers and freaks missions
25. Go to Micheals therapy sessions
26. Fly a plane
27. Collect all nuclear waste
28. Hijack a money truck and take the money inside
29. Pour a line of gas near a bunch of cars, shoot the line and watch the results
30. Customize your car
31. Go hunting
32. Take a picture of yourself
33. Buy a car
34. Complete all the stunt jumps
35. Get a private dance at the strip club
36. Complete all rampages
37. Buy a helicopter
38. Go on the internet (Phone or computer)
39. Buy a plane
40. Tow a car with a tow truck
41. Meet/annoy other characters in the game (Example: Trevor can see Micheal and Franklin and can interact with them)
42. Get eaten by a shark
43. Call for a Taxi
44. Change your license plate (Ifruit app)
45. Control your car in mid air
46. Complete all stunt jumps
47. Underwater activities
48. Watch TV
49. Flip people off while in your car
50. Get high
51. Manipulate the stocks
52. Yoga
53. Collect all spaceship parts
54. Go to the movie theater
55. Send people to Altruist Cult
56. Get drunk
57. Complete all the “Under The Bridge” challenges
58. Increase your skills
59. Get your car washed
60. Ride a bike
61. Visit Grove Street
62. Compete in a Triathlon
63. Buy guns
64. Play darts
65. Smoke
66. Look for myths (Example Bigfoot)
67. Speak to the female officer in Sandy Shores to get 2 star wanted level
68. Get tazed in Sandy Shores by hillibilly and wake up on train tracks infront of incoming train
69. Land and water races
70. Customize guns
71. Practice shooting at the shooting range
72. Taxi missions
73. Motorcycle skydive
74. “Make it rain” or be cheap by giving just a dollar at the strip club
75. Read the news – News can contain your recent mission news, triathlons ect
76. Change the weather to rainy, snowy or sunny (Using cheats)
77. Fly the Atomic Blimp (DLC)
78. Plan your heists
79. Flirt with a stripper and take them home
80. Collect all letter scraps
81. Go on an old fashioned killing spree and get 5 star wanted level
82. Jump of the highest mountain and open your parachute
83. Buy properties
84. Control your car hood in convertibles
85. Flight School
86. Bounty hunting
87. Explore the whole map
88. Play missions (Of course!)
89. Play GTA Online (Next month)
90. Get 100% completed

Also check out what you can do in GTA Online which is out next month! http://thisgengaming.com/2013/09/22/things-you-can-do-in-gta-online/

GTA V REVIEW: http://thisgengaming.com/2013/09/25/gta-v-review/

If I’m missing any things then please leave a comment and I’ll add it to the list.

Credit

1987_EC and Jesse Pinkman from http://gtaforums.com