I love making lists even more than reading them, so here you go.
Graphics - Textures
I'm not a big fan of the retextures that've been done for Morrowind so far. mikeandike's efforts, though, are just too good to be missed:
http://www.nexusmods.com/morrowind/mods/43915/?
http://www.nexusmods.com/morrowind/mods/43091/?
http://www.nexusmods.com/morrowind/mods/43083/?
http://www.nexusmods.com/morrowind/users/3222944/?tb=mods&pUp=1 has been mentioned before here. The only head replacer worth trying, imho. Made from scratch but true to vanilla.
If you include this in your list, make sure you also include the various hair replacers that adopt the vanilla hair styles to MacKom's meshes.
Graphics - Meshes
Another modder with a great attention to detail is PeterBritt. He's recently done amazing, vanilla-friendly remakes of the Nix-Hound and Cliffracer:
http://www.nexusmods.com/morrowind/mods/43620/?
http://www.nexusmods.com/morrowind/mods/43925/? (with transparent wings!)
The https://sketchfab.com/models/6dde89fa6bea48299fe8c55626f2a2e4 he's included are bound to make you drool. Includes fresh textures as well.
A few mods that greatly improve on weapon meshes. Wouldn't play without them:
http://www.nexusmods.com/morrowind/mods/43120/?
http://www.nexusmods.com/morrowind/mods/43484/?
http://www.nexusmods.com/morrowind/mods/43077/?, which builds on http://www.nexusmods.com/morrowind/mods/34844/?
http://www.nexusmods.com/morrowind/mods/34863/?
http://www.nexusmods.com/morrowind/mods/29906/?
An older mod that's done the same for armour:
http://www.nexusmods.com/morrowind/mods/34588/?
You could also count that as a mesh fixer for Better Bodies. I'll leave it up to you if you want to add more of those.
General Fixes - Meshes
There are quite a few mesh collections out there, which contain bug fixes as well as general improvements. Since there's a lot of overlap, I'll list them here in the order I load them in.
http://mw.modhistory.com/download-90-13384 (this version's newer than the one on Nexus)
http://www.nexusmods.com/morrowind/mods/42343/?
http://mw.modhistory.com/download-90-6088
http://www.nexusmods.com/morrowind/mods/42343/?
http://www.nexusmods.com/morrowind/mods/43266/?
There's more of those out there but it starts to get real muddy with a lot of files overlapping.
Also: http://www.fullrest.ru/files/Complete_Armor_Joints, http://www.nexusmods.com/morrowind/mods/18108/?, both of which are included in http://www.nexusmods.com/morrowind/mods/42509/? (another BB mesh fixer).
Bug Fixes
http://www.nexusmods.com/morrowind/mods/43808/?, an obscure typo correction
http://www.nexusmods.com/morrowind/mods/43828/?, does some stuff that the MPP doesn't
Additions
mikeandike is/are also doing a great series of mods that, essentially, beautifies the towns of Morrowind by adding buildings that aren't reachable.
This is the latest in the series: http://www.nexusmods.com/morrowind/mods/43939/?.
http://stuporstar.sarahdimento.com is still alive and kicking, but your link needs an update.
Miscellaneous Interesting Stuff
http://www.nexusmods.com/morrowind/mods/1415/? finally puts all your ingredients in a bag
http://www.fliggerty.com/phpBB3/viewtopic.php?t=1300 does the same for keys
http://adul.net/?p=dl_mwmods_take_gold lets you loot just the gold from a container by assigning a hotkey
http://adul.net/?p=dl_mwmods_weapon_charge_indicator does what it says on the tin
http://www.nexusmods.com/morrowind/mods/43140/?, in the mean time, has been improved by a guy on Nexus. So you might wanna update your link.
http://mw.modhistory.com/download-26-2604, imho the best critter and Cliffracer pacifier out there. Creatures will still attack if you stay in their aura for too long.
And there's still more! But this should do it for now.