This is my UI as of patch 6.0. I'm constantly tweaking/filtering out/adding new stuff as needed, so if you see something in action that isn't listed here, feel free to ask about it!
Addons that come with the LUI package:
Bartender4 - Button placement.
ButtonFacade - Makes buttons pretty.
Grid - Disabled and replaced by Healbot.
Omen - To the right of the chatbox.
Recount - Replaced by Skada; located to the left of my raid frames.
Embedded oUF - Background stuff that makes LUI work.
1) Deadly Boss Mods - Your standard boss mod. I personally prefer DBM over BigWigs, but this is preference simply because I've been using DBM since I started raiding all of those many years ago.
I'm currently using a DBT-Template that allows me to use different skins for my bars (link to a similar file, if not the same file...it's been a while since I've acquired it). Upside: shiny, customizable bars. Downside: needing to redrop the template into the DBM core file every time DBM pushes out an update. An extra step on update days, but easy enough when the template file is kept handy.
2) MikScrollingBattleText - This addon creates a lot of text on a screen that may or may not be actually useful to you unless you use Fraps/OBS and watch the numbers roll in. I like to use this spam as quick references. I'm constantly filtering/tweaking/readjusting the position of MSBT to try and get the most out of all the information it provides. Currently I only display misses, parries, dodges, and crits. Everything is kept relatively faded out and static to minimize useless noise, while still giving me the information I prefer to see.
3) NugComboBar - A great addon to help any class that has a combo point or stacking combo point system, which is to say nearly everyone. It tracks Maelstrom procs, feral combo points, rogue combo points, hunter pet focus, holy power, Soul Shards, Shadow Orbs, as well as quite a few other abilities that seem to be escaping me at the moment. In the screenshots above, the purple orbs are my stacks of Maelstrom Weapon, while the red bar is an indicator of my Searing Stacks.
4) TotemTimers - This addon offers up a lot of different tracking options for shaman, but I really only use it for its namesake: totem timers. I like that it shows me how long a totem has left and when it'll be up again, even though the latter is duplicate information for me.
5) TimeToDie - A great addon to help you gauge whether or not your raid's current dps output will be able to beat that 3/5/whatever minute enrage timer.
6) Error Monster - Notice a certain lack of "That ability isn't ready yet." spam at the top of my screen? Yup, that's Error Monster. It filters out both the visual and audio spam that can occur during a fight. You can set up the filters to whatever extreme you prefer, but I've pretty well just filtered out all of it to help clean up an already chaotic visual/audio interface.
7) Healbot - My preferred healing mod that I've been using since The Burning Crusade. I've been sorely tempted to swap to Vuhdo a few times, but just as I'm about to finally take the dive, HB releases a fix to whatever major bug it was having.
8) Quartz - I love Quartz for its sleek look and for its accuracy, Each bar hangs out slightly beneath their respected unit frames for easy visual acces; my cast bar is just a bit below my unit frame, my target's below their unit frame, focus target's just below their frain.
In this shot you can see where my various bars lay with Bartender. The box on the right-ish side of the screen is where my Naga mouse bindings hang out, which has been made to be fade out at all times and invisible/click through during combat. You can easily see where both my right and left hide-away bars are located. My extra-almost-never-used-buttons, extra mounts, and professions clusters all hide until I mouse over them to help clear up screen space. Bartender pretty much makes my life as an engineering shaman tolerable. So many damn buttons...
Addons you may or may not notice.
Button Facade (now Masque apparently) + Darion - Just makes my buttons a bit prettier, as well as helps to make them stand out a bit more.
Tidy Plates - Love Tidy Plates. Seems to make clicking on a target a bit easier and makes things look a bit less chaotic with multiple nameplates than the standard ui does.
Raid Target Icons & Flares - I needed an addon that enabled me to place raid flares. This is definitely a nifty little addon, though I don't need to use the Icon portion of it due to...
Simple Raid Target Icons - Double click on something/someone and a wheel will appear. Chose your icon of choice and BAM, they're marked. I really do enjoy using this addon for marking adds quickly, since I'm not one to bind macros for this sort of task.
Quality of game play addons.
Mapster - Turns my giant map into a smaller one that can be pulled up while still being able to see.
Mapster + NPC_Scan Overylay
_NPCScan - As many of you have guessed by now, I am a hunter of rares. I would have missed many a kill and tame if it wasn't for this addon and its counterpart, _NPCScan Overlay.
Atlas Loot - For all those data base search needs. Lists loot of every boss in the game, craftable items, tier sets, tabards, and so much more.
clsaver - Automatically enables combat logging when you enter a raid instance while in a raid party. Never forget to log!
Postal - Allows select and mass looting of your mailbox.
Bug Grabber + Bug Sack - Catches errors, records them, and helps to prevent a lot of LUA spam.
IdiotCheck - Do you often head into a raid, forgetting all about your fishing/cooking/Safari until a few pulls in? Are you bad about remembering to enchant your items? This addon just might be for you. On any ready check, this addon will scan your gear, looking for any faults. You can adjust which faults you would like flagged (PvP gear, anything below a certain ilvl, etc) as well as which insult(s) it will throw at you any time something is amiss. Not all of the "insults" are PG, so fair warning.
Since I still get asked about certain addons now and again, I'll mention them here.
ArkInventory - I began using this addon prior to the implement of the search feature into the standard UI. This addon not only turns all of your bags into one giant bag, but allows you to search all of your alts simultaneously for a certain item, view an alt's bags, and will restack/sort all of your items if you tell it to, plus more! Super handy addon to have, though a bit heavy. There are alternatives out there that run a bit lighter, but ArkInventory is my personal favorite.
Bags and Bank (Post Void Storage)
Disabled ArkInventory for the Guild Bank
Today's bags, LUI
Reason I uninstalled: As much I love ArkInventory, it really is a resource hog. AI was ditched in an effort to try and better my in game performance. These days I've opted to use the bag module included in LUI, though it really doesn't have the nice features of AI.
1) ForeXorcist - I get asked about this addon a LOT. This FX is both my cooldown slider bar and my DoTimer. It can track pretty much every thing; DoTs, internal proc cooldowns, ability cooldowns, you name it. Unfortunately it hasn't been updated in a long time, therefor it's pretty buggy. I've actually tried disabling the cooldown slider all together, simply because it's information that I rarely use, but it won't stay off. FX is a huge use at your own risk addon, one that may very well be completely broke come patch 5.4. If it does break, I'm going to be really sad, especially since FX has plugins for LUI so everything looks all nice.
Reason I uninstalled: It was an addon that was semi kept alive by a few folks, but even the Frankenstein reworks bogged my system down something fierce. The reworked version still works great for a few people, but it unfortunately had to go for me. After having it uninstalled for a while, I've also come to realize that (for me) it was just a bit of extra unneeded visual noise. Useful if you want/need more of a visual to show you when CDs are ready (and you're not already using TellMeWhen), but I find timers located on my abilities to suffice.
6) ShieldsUp - I originally picked this addon up during Heroic Spine of Deathwing progression to help me track my Water Shield. With the changes to both Water and Lightning Shields (they're now both constant buffs that just need to be refreshed after a death/once an hour) you'd think that this addon would have become useless. Wrong! I still use Shields Up to keep track of the number of Earth Shield charges I have on a target as Restoration and it will also track the number of Fulmination stacks I have as Elemental. It's sometimes also a nice glaring reminder that I don't have Lightning Shield on as Enhancement, in the odd event that I forget about it or had been recently MC'd during an encounter and the boss gave me Water shield.
Reason I uninstalled: I still rather enjoy this addon, but for the life of me I haven't been able to get it to work properly on my new PC. It may return if I ever find myself seriously healing again (highly doubtful this will ever happen), but otherwise it'll stay retired for now.
OmniCC - Changes how your cooldowns are displayed on your ability buttons. Looks great and is incredibly accurate.
Reason I uninstalled: LUI has a similar function built in. It isn't as exact as OmniCC is, however it does get the job done. Because of this, I ditched the duplicate addon. OmniCC is a really nice addon, so if your UI doesn't already have that function available, I recommend picking it up.