WowAce

Reno is a slash-command that can patch predefined options in a macro to change which abilities will be chosen.

A tool to appraise, estimate, or judge your equipment against the equipment of others.

Tells you the Tiller, what food they like, and if you have fed them today for the quests A Dish for ...

Friends & Guild Data Broker plugin.

Tracks profession specific cooldowns and items across all your characters

FuBar_ChatAlertsFu

Teleporters in Suramar? Sure, why not?

Pet Theory

Displays the zone level ranage of the zone you are in and also gives you a suggest zone and instances to be in.

Library providing mappings between trade skill recipes, spells and created items

ShadowGreenLight helps you decide if recasting SWP/Corruption is worthwhile

Display an informational fighter jet style HUD while flying or riding

NextStep

LilSparky's Workshop mod for Trade Skills

Timerbar embeddable library

Shows a circle on the minimap to indicate spell range

T_Tracking

Monitor the remaining duration on your Mysterious Eggs and other perishable items.

Shared handling of media data (fonts, sounds, textures, ...) between addons.

A Data Broker display for combat statistics.