I'm a massive fan of modding TES games up the wazoo, so I should post what I'm using I suppose?
Realistic Ragdolls and horse
Lost my immersion every time a critical arrow from my assassin launched somebody 15ft off a ledge, so I installed this. Gives dead actors more weight and friction so that they fall faster (more realistically) and slide less. No more chasing dead bandits down a steep hill!
Bandolier - Bags and Pouches
Increases your carry limit by letting you craft pouches, bandoliers, knapsacks and the like. Very neat little thing.
Divine Punishment for Mention of Arrows in the Knee
Haven't seen this in action yet, but it punishes town guards with a deadly lightning bolt at mention of the forbidden catchphrase. Guards respawn though, so it's okay.
The Cartographers Map Markers
Adds more map markers to the main overview, allowing you to jump to specific buildings in cities without having to go inside first. Not sure if I like this one yet as it tends to make looking at quest objective markers in cities a little difficult.
Improved Skill Books
Appends skill books with the skill raised in square brackets. It also sends it directly to your inventory instead of opening it when you pick it up so you can use that valuable skill increase when the level's high and difficult to train.
Diamond Weapon Smithing: Archery
Haven't played around with this much, and although I dislike adding things that unbalance the game greatly, this looks like it's a pretty good trade off between expense and power. You can use flawless gems (garnets, diamonds, amethysts etc) and rare alchemic ingredients (glowing mushrooms, giants toes, etc) to make magic arrows and magic bows. I've only unlocked the frenzy arrow and a stagger arrow at the moment (the skill's tied to smithing) but it's good fun. The stagger arrow stacks with the archery stagger skill and knocks people back - helped me survive my first draugr temple guardian fight!
Item Sorting
Works well with SkyUI (as mentioned by FJ) and categories things so that they're all listed neatly. Prefixes such as Bone:, Ingot:, Food:, Drink:, etc means things are sorted very well and are easier to locate in a full inventory.
Reduced Distance NPC Greetings
AKA the "Silence is Golden" mod. You have to be nearer people before they say stupid things to you. Feels a little more realistic when running through a crowded street.
Wear circlets with hoods
Makes sense. Also works with dragon-priest masks.
Elvenwood
A wood-elf village in the treetops. I haven't actually stumbled across it in game yet, so I can't comment. Looks pretty cool though.
Birds and Flocks
Adds more birds, and flocks of birds. Makes the world seem a little more real and a little less barren.
Auto Unequip Arrows
Think you look silly in third-person when your greatsword's piercing your arrow quiver? (oor-er) This mod removes your two-handed-weapon from your back when you've got a bow equipped, much neater.
Crimson Tide - Blood
Adds spurting arteries and arches of blood to heavily wounded enemies on death, dependent on where you clobber them.
Whistle
Can't find your horse? Use this "spell" to whistle for it, and it'll come galloping over from wherever it is. Think of Gandalf's whistle for Shadowfax.
Lightweight potions
Yep. They're too heavy and I like a lot of them at my disposal.
5kg Dragon Scales/Bones
Again, really fucking heavy. I installed this for my Barbarian who was aiming for dragonbone armour, but switched to a new character before he could even craft daedric. Oops.
Better Quest Objectives
Essential, in my opinion. Replaces vague quest objectives with more specific wording and corrects location of some quest markers. No longer do you have to guess where on a 20 mile road you're meant to be going, it'll say it's between town X and Y and give you a helping hand.
Stones of Barenziah Quest Markers
For the collector.
Horse Armours
They just look better. I haven't bothered crafting any as I don't really use mounts (they die too often!), but it adds armour to horses that are ridden around by other actors.
RNG (Dynamic) Guards
Just better guards. No longer all the same face, same dialogue, same guard. They have individual armours and clothes depending on the location of the hold they're stationed at.
Legible Road Signs High Res
Makes blurry road signs legible. Maybe the official High Res DLC fixes this, but my PC is too poopy to handle any of that.
Dynamic Merchants
Lots of options to make merchants more realistic. I have it set to let them accumulate more gold the more I use them for selling to, and to have more gold in the morning than they do at night (as they spend it as the day goes on restocking).
Phew.
