hello,
I'm going to try to make a list of some usefull addons + what they do (will try to keep this list updated)
If you want to add something to the list just post it in here
deadly boss mode : this addon will tell you about the important spells on a boss fight (wipe abilities and such) it's usefull when you never did the fight
recount : this addon will let you see the dps/healing/... of the players in your group
althoholic : with this you can check all your chars on your acc + what they have in their bags
auctioneer : this addon will help you with AH : quicker buying and selling items
npcscan : very usefull for finding rare mobs : it will look for them, warn you + tell you which mob it is and even mark him
bagnon : this will combine all your bags to 1 big bag
tidy plates : this will change the health bars above mobs : with this it's easier to see if you have aggro
healbot : this will give you a little help with healing : it will make a window with all the players in it from your group and when you click on it it will heal the player (you have to config which click will do which heal -> left mouse button : healing rain , right : healing surge)
addon control panel : very usefull for activating / disable some addons while ingame. this saves some time
titan panel : this addon will give you a bar with some details in from your char/acc like total gold,durability,empty bag spots,time,...
gatherer : this addon will place all herbs,ores,fishing pools,.. on the map (you have to find the herb and such otherwise they won't show up on the map this addon just remembers the place of it)
gathermate : this addon works together with gatherer . it will place all the herbs,ores,... on the map without that you will need to find them first
badboy : usefull addon against gold sellers : it will give you a message when they try to whisp you and gives a button to report them
GTFO : addon that will give a sound when you stand in bad shit like fire and such (can be annoying sometimes)
routes : this will draw lines across the way you need to fly when you are herbing/mining (you select which herbs and such) gatherer is needed for this addon!!!
tradeforwarder : this addon will let you see trade chat EVERYWHERE only bad part of it is that you can't talk in it when you are outside the city
rangedisplay : usefull if you need to know how far you are away from your target (can go up to 100yards if i'm right)
buffenough : this will tell you if you have all the buffs that are possible
reforgelite :this addon will help you with reforging your gear : tell you which stats are the best for you
oQueue : oQueue is wow's first mesh network implementing a x-realm premade finder which enables users to see groups forming up to for:regular battlegrounds,rated battlegrounds,scenarios,dungeons,raids
VuhDo : never used it myself but seems to be another version of healbot
prat : adds some more information of the players who are talking in chat + timestamps and much more (check description on curse)
MrPlow : this addon gives you 1 big bag + the option to sort your bag
Postal : this addon will help you empty your mailbox : 1 button to take all mails out
Juked : displays whenever players use their interrupts or cooldowns (configurable)
castbars : this will change the casting bars to make it look better (didn't use the addon myself Praga suggested it together with some other addons)
World Boss Status : tells you if you did the world bosses in MOP (credits go to nagashi )
And ofcouse zygor : this guide/addon will help you with almost anything that you need to do in-game : leveling,getting rep,dailies,achies,proffs,...
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addons that are posted by other members (after 03/10/2013)
ArkInventory : This is an addon similar to bagnon but you are possible to do some configs + make a filter in your bags for example rp items
SilverDragon : An addon who tells you if there is a rare mob near you + when you last saw them
Omen Threat Meter : gives a list of the threat of other players
Mapster : This addon reveals whole map
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actionbarsaver : saves macros and spots where the spells are usefull for spec swap without puting spell/macros out (also restores deleted macros)
affdots : tells you how much better your damage over time spells will be if you refresh them right now
atlasloot : shows you dungeon drops
overachiever : tells you things about achievements (have you /loved this critter) and stuff
quartz : customizable cast bar
scrap : sells all the items you dont need
tomtom : gps
vanaskos : tells you when players are nearby (even stealthed rogues) and you can add them to kill on sight lists and such
weakauras : completely customizable displays, you can make meters and things that alert you
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(updated on 13/2/14)
MoveAnything : you can replace everything in your screen.
bartender4 : Bartender4 is a full ActionBar replacement mod. It provides you with all the features needed to fully customization most aspects of your action and related bars.
decursive : Decursive is a cleansing mod intended to make affliction removal easy, effective and fun for all the classes having this ability.
pettracker : PetTracker is a tool designed to help all kinds of trainers in their pet tracking and battling duties.
Omni-cc : OmniCC is an addon that adds text to items, spell and abilities that are on cooldown to indicate when they will be ready to use. In other words: it turns all the standard analogue cooldowns into digital ones.
Raidachievements : tells you when you got everything that is needed for the achievement in a raid or when it is failed.
WIM(wow instant messenger) : this will place your whispers into a different window (makes chatting easier).
tellmewhen : TellMeWhen provides visual, auditory, and textual notifications about cooldowns, buffs, and pretty much every other element of combat.
healers have to die (mostly pvp) : Spot those bloody healers instantly and help them accomplish their destiny! (PVP and PVE).
questhelper : this helps you to find the quickest way to complete your quests (similar to zygor but zygor is better (advertise )
collect me : Collect Me keeps track of your mounts, companions and titles in the game and can show you what mounts, companions, titles you're missing with additional information on where to get them.
cooldowns : this shows the cooldown of your abilities (digital numbers) .
Quartz : replaces your casting bar.
reforgelight : ReforgeLite is a lightweight reforging calculator that helps you figure out the optimal strategy to reforge your gear given your stat weights and caps without leaving the game.
Grid : Grid is a compact and highly configurable party/raid unit frame addon.
WeakAuras : WeakAuras is a powerful and flexible framework that allows you to display highly customizable graphics on your screen to indicate buffs, debuffs, and a whole host of similar types of information.
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(updated on 25/4/14)
Action bar saver : it lets you save talents/macros layout on the bars so if you were to change your current build to arcane from frost you can delete every macro and setup arcane ones and restore etc (ty empty_skillz for posting this addon)
All these addons are downloadable on curse except zygor you have to pay for this addon. Or you need access to the elite section