First things first, don't confuse IOS with ISO. Obviously, much different.
IOS is the operating system that runs on the Starlet coprocessor inside the Hollywood package. It provides services that are used by Wii code to access many system devices: USB, networking, security, app management, NAND flash storage, SD card, optical disc, and also WiiConnect24 features.
List of IOS's (does NOT include cIOS's!!)
IOS3 (versions 65280): Is a stub. A supported theory is that there are non-stub versions of IOS3 (only on NDEV Wiis), but when Pinkfish was leaked, Nintendo sent this stub on Wii Updates to prevent users from using IOS3 to install dev certs via Pinkfish.
IOS4 (versions 1, 3, 259, 65280). Version 3 used by the 'Pre 1.0' system menu aka Wii Startup Disc Menu. Remnants of a version 1 were discovered within the leaked 'Wii Startup Disc NAND'. Version 65280 is a stub. Non-stub versions are very basic and only contain minimal drivers.
IOS5 (version 514). Completely no information about this IOS. Can't be found on any normally purchased Wii, not found on any Wii Updates.
IOS9 (versions 1, 516, 518, 520, 521, 778, 1034) Version 1 found on the 'Wii Startup Disc NAND'. Other versions used by System Menu 1.0.
IOS10 (version 768) Version is a stub, first ever stub IOS released by Nintendo for Wii Updates.
IOS11 (versions 10 and 256) Used by System Menus 2.0 and 2.1. Version 256 is a stub.
IOS12 (versions 6, 11, 12, 269, 525, 526) Version 6 is the earliest known IOS with a time stamp of June 4th, 2006
IOS13 (versions 10, 15, 16, 273, 1031, 1032) Used by Photo Channel 1.0 and versions 2 & 3 of Mii Channel. Used by the 'system' component for Weather and News channels.
IOS14 (versions 257, 262, 263, 520, 1031, 1032) No additional info
IOS15 (versions 257, 258, 259, 260, 265, 266, 523, 1031, 1032) No additional info
IOS16 (versions 257, 512) Version 257 used by Pinkfish disc. Version 512 sent by Nintendo as a stub to stop hacks that used IOS16.
IOS17 (versions 512, 517, 518, 775, 1031, 1032) Used by early games such as Super Paper Mario.
IOS20 (versions 12, 256) Used by System Menu 2.2. Version 256 is a stub.
IOS21 (versions 514, 515, 516, 517, 522, 525, 782, 1038, 1039) Commonly used by 3rd party games.
IOS22 (versions 772, 777, 780, 1037, 1293, 1294) Version 772 from an early update disc.
IOS28 (versions 1288, 1292, 1293, 1550, 1806, 1807) Starting with this IOS, IOS's came in 15 modulated parts.
IOS30 (versions 1037, 1039, 1040, 2576, 2816) Used by System Menus 3.0, 3.1, 3.2 and non-Korean 3.3. Added USB keyboard support. Version 2816 is a stub.
IOS31 (versions 1037, 1039, 1040, 2576, 3088, 3092, 3349, 3607, 2608) Used by Weather, News, Mii, and Photo 1.1 channels.
IOS33 (versions 1040, 2832, 2834, 3091, 3607, 3608) No additional info.
IOS34 (versions 1039, 3087, 3091, 3348, 3607, 3608) No additional info.
IOS35 (versions 1040, 3088, 3092, 3349, 3607, 3608) No additional info.
IOS36 (versions 1042, 3090, 3094, 3351, 3607, 3608) Used by Mario Kart Wii (except the Korean version) and Brawl. IOS commonly patched for HBC.
IOS37 (versions 2070, 3609, 3612, 3662, 3869, 5662, 5663) First IOS sent by Nintendo to fix the signature signing bug (Trucha Bug).
IOS38 (versions 3609, 3610, 3867, 4123, 4124) Used by Animal Crossing (except the Korean version), and added support for Wii Speak.
IOS40 (versions 2321, 2835, 3072) Korean IOS. Used by System Menu 3.3K. Version 3072 is a stub.
IOS41 (versions 2320, 2835, 3091, 3348, 3606, 3607) Korean IOS
IOS43 (versions 2320, 2835, 3091, 3348, 3606, 3607) Korean IOS
IOS45 (versions 2320, 2835, 3091, 3348, 3606, 3607) Korean IOS
IOS46 (versions 2322, 2837, 3093, 3350, 3606, 3607) Korean IOS. Used by Korean Version of Mario Kart Wii, Korean Version of Need for Speed Underground, and Korean Version of Shin Chuukadaisen
IOS48 (versions 3867, 4123, 4124) Korean IOS. Used by Korean Version of Animal Crossing. Came with the 4.3K System Menu update. Similar to IOS38 but has certain updated modules.
IOS50 (versions 4889, 5120) Used by System Menu 3.4. Version 5120 is a stub.
IOS51 (versions 4633, 4864) Came with the System Menu 3.4 update for the Shopping Channel version at the time. Also used to fix more signature signing bugs.
IOS52 (versions 5661, 5888) Korean IOS. Used by System Menu 3.5K. Version 5888 is a stub.
IOS53 (versions 4113, 5149, 5406, 5662, 5663) Used by Wiiware. Version 5406 used by Monster Tri Hunters.
IOS55 (versions 4633, 5149, 5406, 5662, 5663) Changes to DI module. Version 5406 used by Monster Tri Hunters.
IOS56 (versions 4890, 5146, 5405, 5661, 5662) Used by Wii Speak 2.0 and Shopping Channel v20.
IOS57 (versions 5404, 5661, 5918, 5919) Used by DragonQuest X. Came with updated USB modules for DragonQuest's USB Hard Disk support.
IOS58 (versions 5918, 6175, 6176) IOS used by HBC 1.0.7 and newer. Added support for USB cameras to allow the game "Your Shape" to work.
IOS59 (versions 6689, 7201) Released for same reasons of IOS57.
IOS60 (versions 6174, 6400) Used by System Menus 4.0 and 4.1. Version 6400 is a stub.
IOS61 (versions 4890, 5405, 5661, 5662) Used by HBC 1.0.6. Used by Shopping Channel v21. Used by latest revision of Photo Channel.
IOS62 (version 6430) Used by Wii U Transfer Tool.
IOS70 (versions 6687, 6912) Used by System Menu 4.2. Version 6912 is a stub.
IOS80 (versions 6943, 6944) Used by System Menu 4.3.
IOS222 (version 65280) Piracy prevention attempt to stop Herme's cIOS
IOS223 (version 65280) Piracy prevention attempt to stop Herme's cIOS
IOS249 (version 65280) Piracy prevention attempt to stop any kind of cIOS 249.
IOS250 (version 65280) Piracy prevention attempt to stop any kind of cIOS 250.
IOS254 (versions 2, 3, 260, 65280) Version 65280 came with System Menu 4.3 update as an attempt to stop PatchMii. Version 2 is an exact copy of IOS9v520. Version 3 is an exact copy of IOS9v521. Version 260 is an exact copy of IOS9v778.
IOS is the operating system that runs on the Starlet coprocessor inside the Hollywood package. It provides services that are used by Wii code to access many system devices: USB, networking, security, app management, NAND flash storage, SD card, optical disc, and also WiiConnect24 features.
List of IOS's (does NOT include cIOS's!!)
IOS3 (versions 65280): Is a stub. A supported theory is that there are non-stub versions of IOS3 (only on NDEV Wiis), but when Pinkfish was leaked, Nintendo sent this stub on Wii Updates to prevent users from using IOS3 to install dev certs via Pinkfish.
IOS4 (versions 1, 3, 259, 65280). Version 3 used by the 'Pre 1.0' system menu aka Wii Startup Disc Menu. Remnants of a version 1 were discovered within the leaked 'Wii Startup Disc NAND'. Version 65280 is a stub. Non-stub versions are very basic and only contain minimal drivers.
IOS5 (version 514). Completely no information about this IOS. Can't be found on any normally purchased Wii, not found on any Wii Updates.
IOS9 (versions 1, 516, 518, 520, 521, 778, 1034) Version 1 found on the 'Wii Startup Disc NAND'. Other versions used by System Menu 1.0.
IOS10 (version 768) Version is a stub, first ever stub IOS released by Nintendo for Wii Updates.
IOS11 (versions 10 and 256) Used by System Menus 2.0 and 2.1. Version 256 is a stub.
IOS12 (versions 6, 11, 12, 269, 525, 526) Version 6 is the earliest known IOS with a time stamp of June 4th, 2006
IOS13 (versions 10, 15, 16, 273, 1031, 1032) Used by Photo Channel 1.0 and versions 2 & 3 of Mii Channel. Used by the 'system' component for Weather and News channels.
IOS14 (versions 257, 262, 263, 520, 1031, 1032) No additional info
IOS15 (versions 257, 258, 259, 260, 265, 266, 523, 1031, 1032) No additional info
IOS16 (versions 257, 512) Version 257 used by Pinkfish disc. Version 512 sent by Nintendo as a stub to stop hacks that used IOS16.
IOS17 (versions 512, 517, 518, 775, 1031, 1032) Used by early games such as Super Paper Mario.
IOS20 (versions 12, 256) Used by System Menu 2.2. Version 256 is a stub.
IOS21 (versions 514, 515, 516, 517, 522, 525, 782, 1038, 1039) Commonly used by 3rd party games.
IOS22 (versions 772, 777, 780, 1037, 1293, 1294) Version 772 from an early update disc.
IOS28 (versions 1288, 1292, 1293, 1550, 1806, 1807) Starting with this IOS, IOS's came in 15 modulated parts.
IOS30 (versions 1037, 1039, 1040, 2576, 2816) Used by System Menus 3.0, 3.1, 3.2 and non-Korean 3.3. Added USB keyboard support. Version 2816 is a stub.
IOS31 (versions 1037, 1039, 1040, 2576, 3088, 3092, 3349, 3607, 2608) Used by Weather, News, Mii, and Photo 1.1 channels.
IOS33 (versions 1040, 2832, 2834, 3091, 3607, 3608) No additional info.
IOS34 (versions 1039, 3087, 3091, 3348, 3607, 3608) No additional info.
IOS35 (versions 1040, 3088, 3092, 3349, 3607, 3608) No additional info.
IOS36 (versions 1042, 3090, 3094, 3351, 3607, 3608) Used by Mario Kart Wii (except the Korean version) and Brawl. IOS commonly patched for HBC.
IOS37 (versions 2070, 3609, 3612, 3662, 3869, 5662, 5663) First IOS sent by Nintendo to fix the signature signing bug (Trucha Bug).
IOS38 (versions 3609, 3610, 3867, 4123, 4124) Used by Animal Crossing (except the Korean version), and added support for Wii Speak.
IOS40 (versions 2321, 2835, 3072) Korean IOS. Used by System Menu 3.3K. Version 3072 is a stub.
IOS41 (versions 2320, 2835, 3091, 3348, 3606, 3607) Korean IOS
IOS43 (versions 2320, 2835, 3091, 3348, 3606, 3607) Korean IOS
IOS45 (versions 2320, 2835, 3091, 3348, 3606, 3607) Korean IOS
IOS46 (versions 2322, 2837, 3093, 3350, 3606, 3607) Korean IOS. Used by Korean Version of Mario Kart Wii, Korean Version of Need for Speed Underground, and Korean Version of Shin Chuukadaisen
IOS48 (versions 3867, 4123, 4124) Korean IOS. Used by Korean Version of Animal Crossing. Came with the 4.3K System Menu update. Similar to IOS38 but has certain updated modules.
IOS50 (versions 4889, 5120) Used by System Menu 3.4. Version 5120 is a stub.
IOS51 (versions 4633, 4864) Came with the System Menu 3.4 update for the Shopping Channel version at the time. Also used to fix more signature signing bugs.
IOS52 (versions 5661, 5888) Korean IOS. Used by System Menu 3.5K. Version 5888 is a stub.
IOS53 (versions 4113, 5149, 5406, 5662, 5663) Used by Wiiware. Version 5406 used by Monster Tri Hunters.
IOS55 (versions 4633, 5149, 5406, 5662, 5663) Changes to DI module. Version 5406 used by Monster Tri Hunters.
IOS56 (versions 4890, 5146, 5405, 5661, 5662) Used by Wii Speak 2.0 and Shopping Channel v20.
IOS57 (versions 5404, 5661, 5918, 5919) Used by DragonQuest X. Came with updated USB modules for DragonQuest's USB Hard Disk support.
IOS58 (versions 5918, 6175, 6176) IOS used by HBC 1.0.7 and newer. Added support for USB cameras to allow the game "Your Shape" to work.
IOS59 (versions 6689, 7201) Released for same reasons of IOS57.
IOS60 (versions 6174, 6400) Used by System Menus 4.0 and 4.1. Version 6400 is a stub.
IOS61 (versions 4890, 5405, 5661, 5662) Used by HBC 1.0.6. Used by Shopping Channel v21. Used by latest revision of Photo Channel.
IOS62 (version 6430) Used by Wii U Transfer Tool.
IOS70 (versions 6687, 6912) Used by System Menu 4.2. Version 6912 is a stub.
IOS80 (versions 6943, 6944) Used by System Menu 4.3.
IOS222 (version 65280) Piracy prevention attempt to stop Herme's cIOS
IOS223 (version 65280) Piracy prevention attempt to stop Herme's cIOS
IOS249 (version 65280) Piracy prevention attempt to stop any kind of cIOS 249.
IOS250 (version 65280) Piracy prevention attempt to stop any kind of cIOS 250.
IOS254 (versions 2, 3, 260, 65280) Version 65280 came with System Menu 4.3 update as an attempt to stop PatchMii. Version 2 is an exact copy of IOS9v520. Version 3 is an exact copy of IOS9v521. Version 260 is an exact copy of IOS9v778.