WowAce

Heads-up minimap display

OneBag

Desesperated announcing to clearly show the skillings of act inplay.

Sphere

Heads Up Display with Player and Target Info

Displays information about the current zone on the World Map for WoW Classic Era

Keeps track of time played and rested XP across your characters.

Display front-end for LibGuildPositions-1.0 using HandyNotes

Sheppard

Prints a message in your default chat frame when someone in your group gains an aura.

Tracks the precise arrival & departure schedules of boats and Zeppelins around Azeroth and displays them on the Mini-Map and ...

Collects, analyzes and presents information about the virtual economy.

Keeps track of space left in your bags.

Broken in Midnight. I recommend MidnightFocusInterrupt instead.

NameTagToggle

Keeps track of current money and all your characters on one realm.

Auto roll greed, need, pass or manually roll on items.

Pet Theory

KoS-Management Tool

Estimated time until current target will die.