I've added a whole passel of stuff, and it all sort works- sort of. Mostly, I think the problem is I have too much going on, rather than any specific mod not working, except one. I think that was called Balmora Expansion- it was just released in September, and it rolled a whole bunch of Balmora enhancements together into one mod- when I'd get in the vicinity of the town, it'd crash (I assume it was just too much to load).
The things I've installed have mostly been game-affecting or quests rather than cosmetic enhancements. From memory, here's the list that I have going right now:
Better Bodies 2.0
Better Heads.
Better Aragonian Heads.
Cloak Collection- adds cloaks and hoods, plus magic cloaks and quests to get them
Dodge Mod 1.2 (scripting)- adds a Sanctuary bonus depending on your unarmored skill and armor worn. Makes armor-less characters viable.
TLM (The Lighting Mod) (Heavy scripting)- this changes the way the light works in the entire game. It changes the lighting values everywhere, making light sources brighter, and ambient light lower indoors (and at night). Adds sneak bonuses and penalties based on the light you're in (big penalties for carrying a torch or lantern, frex.), and a 'sneak eye' skill that gives you a Night Eye effect while sneaking (the effect is based on your sneak skill level). All in all really cool, but I think the scripting is part of why the game is crashing.
Wakim's Game Improvements Modular 9-pack(massive rebalancing of everything in the game- I use them all except the NPC Spellcasting one)
Lara Craft (Bretonian Girlfriend- Companion mod)
Witchgirl (Bisexual? Wiccan Girlfriend - Companion) - I just added these to see if they would work as intended. They do AFAIKT, but I haven't done too much with them yet.
Illuminated Order- a pretty big storyline that, among other things, could let you become a Lich!
Suran Underworld - another pretty big storyline that lets you play a badass doing missions for the Mob, GTA-style.
Less Generic NPC Project (several) - These replace the NPCs in Syeda Neen, Gnaar Mok, Ald Veloth, Khuul, and Maar Gan with slightly more interesting people. Nothing major, one or two small quests in each town- they just help with having every NPC in the game saying exactly the same thing.
I'm sure there are a few more, but that's the meat. This all runs flawlessly, except that the game gives me the dreaded DDE when I play too long/ travel to too many areas in a short time. It seems to me that it's all just taking too much space in memory/not cleaning older stuff out often enough. I wish there was a way I could force it to cache that stuff more often.