Healing Mods

Clique

Clique is a simple GUI that lets you assign click-casting for any number of unit frames. Click casting allows you to define the behavior the game takes when you click on a frame. This can be casting spells, running a macro, using an item, or something as simple as changing targets or assisting a unit.
WoWInterface, Curse
Review: WoW Insider

Grid

Grid is a modular, lightweight and screen-estate saving grid of party/raid unit frames. Optional modules can be assigned to up to 7 possible indicators: each corner, a border center text and center icon - to highlight specific units (and if you prefer to only show units in range, this is posible too). Grid comes with a bunch of modules (aggro indicator, incoming heals, auras (debuff types, shield, renew, rejuv, mortal strike,...), mana, health deficit,...), but it's easy to add your own modules (see the developer API).
Curse
Tutorial: Tankspot

HealBot

Allows for 20 key mouse combinations to cast any beneficial spells, Allows for 20 key mouse combinations to cast on disabled bars, Can track and display who has aggro, can be used for decursive functions, can be used for monitoring buffs and buffing, appearance can be configured and preferred appearances can be saved as skins, can show party/tanks/checked targets/extras in a raid, extras can be filtered and sorted, multiple HealBots in a party/raid sync incoming heals, will accurately range check at all times for spells and items, has a built in res monitor and is compatible with CTRA (CTRA not required).
Config: /hb o
WoWInterface, Curse
Review: WoW Insider Pt1, WoW Insider Pt2

Healium

Healium provides a customizable, intuitive, compact, no-clutter interface optimized to make it easy to heal. Healium places your healing spells onto buttons right next to each person's healthbar. The buttons will cast the heal on the person they are beside of, without the need for you to target the person first. Player healthbar's are compact and close to each other which reduces the amount of screen space you have to look over to monitor the party's health. The healing buttons are very close by, minimizing the space you have to move your mouse, and thus the time required, to cast the heal. Unlike other healing focused addons, Healium does not require you to set up complex key combinations (shift, ctrl, and alt) to cast your heals. In Healium, you just click a healing button next to the person's health bar. There is no memorization of key combinations required, or even allowed!
Curse
Review: WoW Insider

VuhDo

Raid monitor similar to CTRaidAssist or Blizzards built-in raid frames. Displays the health of raid members as clearly arranged bars. Healing spells or other actions can be assigned to mouse clicks on bars (Click-Heal). What makes VuhDo unique is its high performance and the variety of configuration options to perfectly fit your needs. Special features: Up to 10 independent heal panels - Combat log parsing for faster health updates - Panel configuration via drag-n-drop - Health, debuff, mana, aggro, range monitoring in just one view.
Curse, WoWInterface
Tutorial & Review: WoW Insider