WowAce

"Debug" code free since '93!

A modular, lightweight and screen-estate saving grid of party/raid unit frames

Arena unit frames

Another HUD addon

Dog-themed unit frames. Woof. Arf. Yip.

Replaces the normal unit, party, target, pet frames and adds target-of-target.

HideTalkingHead

Plugs classical world style fonts into LibSharedMedia-3.0

A Friend-Enemy-Unit-Frame for battlegrounds.

Adds Buff/Debuff icons to the grid frame.

Threat reactive nameplates for TidyPlates.

Adirelle's unit frames, based on haste's oUF.

Shows class colors on player nameplates and names

An extension to the default WoW Unit Frames.

Kiwi Plates

Adds manabars to the sides of Grid frames.

EUF is an enhance of wow original unit frames, provides hp with both value and %, and optional 3D portrait. Simple and Useful.

Adds custom layouts for Grid

Show who is targeted by at least one enemy, and the casting progress of the incoming spell.

Aloft