WowAce

Provides quick access to information on your group and their equipment, enchant and gem choices.

GrindStatus

Where the lore is at

Show all the leyline taps in Suramar

Makes a sound when your focus starts casting. Use with [target=focus] macros for interrupts (Counterspell, Spell Lock, Wind ...

Checks your gear before bosses and yells at you if you're an idiot

LDB display of currencies, gold totals and session / daily / weekly statistics for all characters on a server.

Textures for Stop Motion

Display Garrison missons for all Characters

Proximo

Death analysis tool

Find five Ephemeral Crystals, get a pink hippogryph

Shows ZoneInfo on the World Map in a perfectly cromulent fashion.

Questing minion

Keeps track of your current location.

Enhances the default AddOns list.

Allows you to preview weapon glow in Dressing Room.

Switch macro depending on zones or BigWigs boss modules.

Says random things in chat when casting any spell or ability. Type "/ss help" for the user's manual.

HUD that you can tweak the way you want.