Rewatch
Summary
Rewatch is an addon to help you monitor your healing-over-time (HoT) spells as a druid. There's an easy main window which you can move around, which will contain six bars for every target; a healthbar, energy-/rage-/manabar, lifebloom bar, rejuvenation bar, regrowth bar and a wild growth bar. Simply click a spell bar to cast that spell on that specific player and watch the clicked bar channel down as the corresponding HoT spell runs out.

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VisualHeal is a small and simple but powerful tool for all classes that visually shows your heals to others and heals incoming to you from others by means of two information-packed, yet intuitive bars:

Nonce displays a graphical indication of which presence is currently active on the edges of the screen.

Description
RuneWatch is a RuneFrame Replacement Addon which has slowly evolved into a UnitFrame for DeathKnights. The Mod tracks your runes, thier cooldowns and also visually represents your Runic Power.

Very Basic Add-on to determine active presences.

Tank Warnings is a simple addon to warn configurable messages upon certain events related to tanking, like Taunt resists or usage of special mitigation abilities that are usually used in emergencies, like Shield Wall and so on.

Shows a small, transparent window indicating a tank's overall avoidance, mitigation, total block value and block cap status (where applicable), guaranteed minimum spell mitigation and per-school average mitigation. Values of each stat change dynamically as new buffs are applied / gear is swapped. Can be set to show figures appropriate to standard level 80 enemies or versus Boss mobs - in the latter case, for instance, block cap is indicated by a 100% rating rather than 102.4%. TankTotals will also (optionally) announce to the raid when a cooldown such as Shield Wall is used and fades, whenever a targetted mitigation ability like Hand of Sacrifice is used, and (for paladins) whenever Ardent Defender prevents what would otherwise have been a death. It will also optionally auto-remove Hand of Protection from tanks.

YssGhoul is a simple addon that reminds you to summon your Ghoul

Yury's RuneDisplay is a simple and lightweight addon to replace Blizzard's RuneFrame