There are pictures of every "i" location and where each is located on the islands map at this website.
http://www.gamespot.com/features/6213637/p-4.htmlDon't remember where I got this list of all 80 "i" locations from or why they are numbered this way. I printed out the list and crossed off the locations I had already found. Then you can go through the Flight Record displays (1-40 & 41-80) in the game (or the pictures of each location at the website above), to see where your remaining locations to find are, on the islands map.
Also, as you get each "i" location, pop all the WHITE balloons found near that location toward earning a stamp. (see the info on all the stamps available)
01: Barnacle Arch
02: Basketball Court
03: Beginner's Archery Area
04: Beginner's Wakeboarding Area
05: Bowling Alley In the city. There is a bowling pin over the building.
06: Broken Clock Tower In the city. It is one of the taller buildings in the area.
07: Cabana Lagoon
08: Camel Rock
09: Cedar Tree Tunnel
10: Cliffside Ruins
11: Cocoba Hotel Located near the beach on the main island.
12: Crab Rock In between two large rocks on Wedge Island, the smaller island with the golf courses.
13: Dead End Point
14: Deserted Island
15: Diving Spot Behind the Private Island. There are two boats in this area.
16: Duckling Lake
17: Entrance to the Mysterious Ruins
18: Evergreen Grove
19: Extreme Canoeist
20: Firework Launch Zone 1
21: Firework Launch Zone 2
22: Footbridge
23: Forest Monument
24: Frisbee Dog Park
25: Gateway to Wuhu
26: Golf Area A On Wedge Island, the smaller island with the golf courses.
27: Golf Area B On Wedge Island, the smaller island with the golf courses.
28: Golf Area C On Wedge Island, the smaller island with the golf courses.
29: Heart of Mahu Wahu
30: Heartbreak Peak
31: Hillside Cabins
32: Hilltop Overlook
33: Island Loop Tunnel 1
34: Island Loop Tunnel 2
35: Lava Monument Inside the volcano. There's a tunnel behind the Lone Cedar into the volcano.
36: Lava Tube
37: Lone Cedar
38: Maka Wuhu
39: Miguel's Guide Plane Scope the entire island for a smoke line or send up a flare with the 1 button and watch for Miguel's flare. Follow Miguel's plane for like 3 minutes to earn a stamp. (see the info on all the stamps you can earn)
40: Moutain Monument
41: Mountain Hikers
42: Mysterious Ruins
43: Needlepoint Spire
44: Off-Road Vehicle
45: Palm Boulevard
46: Pirate's Eye In the hole underneath the Candle lighthouse.
47: Pool Patio
48: Power-Cruising Area
49: Private Island
50: Red Iron Bridge On the bridge that looks identical to the actual Golden Gate Bridge
51: Runner's Circle
52: Sea Serpent Cavern
53: Seaplane Team
54: Serpent's Mouth
55: Silk Sands
56: Sportfishing Spot
57: Starboard Harbour
58: Starry Beach
59: Stillwater Grotto
60: Sugarsand Beach
61: Summerstone Castle Located near the lake on the cliff.
62: Summerstone Falls
63: Sundown Point
64: Swaying Bridge A big wooden bridge near the castle
65: Sweet Beach
66: Swordplay Colosseum Located near the town
67: Talon Rock
68: Tennis Court
69: The Candle
70: The Nineteenth Hole Hotel Located on the golf island
71: The Queen Peach Located in the harbor. It is a large cruise ship.
72: The Sea Caddy
73: The Whale Shark
74: Toppled Monument
75: Undersea Cable Inspectors
76: Weathered Monument
77: Wedge Island Marina
78: Whale Watchers
79: Wind Orchard Located in between all the wind turbines on the main island.
80: Wishing Fountain Located in the center of the city of the main island.