The Police

Here is a list of addons and macros that I use

Addons

Leveling
ClassicCodex - questing addon similar to Questie but shows mob and item spawn locations
Talent Sequence - lets you have your planned out talents in sequence in game so you don't have to remember which ones to select
What's Training? - shows you what class trainer skills are available at what levels

Combat
ClassicAuraDurations - Restores cooldown swipe timers on default Target Frame and Blizzard Raid Frames
ClassicCastbars - Adds castingbars to the target frame and nameplates
Deadly Boss Mods (DBM) - Required especially for raiding. Shows warnings for different boss abilities and phases
Details! Damage Meter - Required especially for raiding. Tracks threat and a lot of different stats like damage and healing done
OmniCC Classic - Shows cooldown text on icons
RealMobHealth - Shows actual health numbers on mobs
VuhDo - The ultimate in raid/party frames, especially for click healing/buffing/decursing. Recommended for all healers.
WeakAuras 2 - can do almost anything in regards to showing buffs, debuffs and other info

Items
AtlasLootClassic - shows you what loot drops from bosses
AtlasLootClassic Maps - Shows maps for bosses in AtlasLootClassic
Auctionator - Adds new features to the auction house
BagFreeSpaceCounter - Shows how many inventory slots you have left on the bag icon
Bagnon - Bag overhaul, shows one unified bag and shows items from other characters/bank
EZJunk - Auto selss your junk
FasterLooting - Auto loots items faster
oGlow (Classic) - Colours item frames based on item rarity
Vendor Price - Shows vendor prices on item tooltips

Professions
GatherMate2 - Shows gathering icons on the map and minimap
ItemTooltipProfessionIcons - Shows what professions items are used for

PvP
Spy Classic - Warns you about nearby alliance players

UI and utility
AutoCarrot - Automatically equips/unequips your Carrot on a Stick, riding boots and riding gloves when you mount/dismount
ChatLinkIcons Classic - Shows item, race and class icons in the chat
ClassicAutoDismount - Auto dismounts when you do an action
ClassicLFG - Interface to streamline looking for groups
FriendsInfo - Lets you add notes to players so you can remember why to group or not group with them etc.
Leatrix Maps (Classic) - A map overhaul with lots of features and improvements. A must have!
MapCoords Classic - Shows your coordinates on the minimap
RingMenu - Adds a circular hotbar around your mouse that you can open with a keybind
TipTac for Classic - Highly customizable mouseover tooltip addon, also lets you anchor tooltips to mouse
Titan Panel Classic - Adds a top panel with lots of different information like xp/hr, gold, bag space and item durability
Trinket Menu Classic - Adds a small 2 slot trinket menu that lets you activate trinkets and switch trinkets easily

Multiboxing
EMAC (Ebony's Multiboxing Assistant Classic) - Adds several utilities for running more than one character at a time
ISBoxer - Not an addon, but the software I use to run multiple instances of WoW and to map keys etc.


Macros

General info
[@mouseover, help] - tries to cast on mouseover target if friendly
[help] - tries to cast on target if friendly
[@targettarget, help] - tries to cast on assist target if friendly
[] - default cast behaviour
"harm" can be used instead of "help" to target enemies

Spam to tag mob macro:

#showtooltip
/cleartarget [dead][help]
/targetenemy [noexists]
/cast Fire Blast

Interrupt and cast harmful spell with mouseover and assist targeting:

#showtooltip
/stopcasting
/stopcasting
/cast [@mouseover, harm][harm][@targettarget, harm][] Counterspell

Interrupt and cast helpful spell with mouseover and assist targeting:

#showtooltip
/stopcasting
/stopcasting
/cast [@mouseover, help][help][@targettarget, help][] Renew

Interrupt and cast spell on either friend with mouseover or targeted friend or enemy:

#showtooltip
/stopcasting
/stopcasting
/cast [@mouseover, help][help][] Dispel Magic

Interrupt and toggle Ice Block, cast Cold Snap if Ice Block is on cooldown:

#showtooltip
/stopcasting
/stopcasting
/cancelaura Ice Block
/cast Ice Block
/cast Cold Snap

Simple priest DPS rotation macro. Will reset when changing target or after 20 seconds.

#showtooltip
/castsequence reset=target/20 Holy Fire, Shadow Word: Pain, Smite, Smite, Smite, Smite, Smite

Buy rare merchant item macro spam
1. First make a macro and bind it to a key. Replace 38 with the merchant item slot that the rare item shows up in, 38 is for Qia in Winterspring.

/run BuyMerchantItem(38)

2. Bind interact to a key close to the macro key.
3. Target the merchant in question.
4. To spam you use interact (to open the merchent window) -> Then you use the macro key to buy the item -> Then you press esc to close the merchant window -> repeat.