Quiet often depending on your spec you can run into situations where you need to pay attention to spell and talent procs. When your in a raid and have a large amount of buffs this can be rather hard to do. There are two AddOns that I would recommend, Event Alert & Power Auras

Power Auras

This mod has all the bell’s and whistles you could possibly want but all the options can be rather intimidating especially if your not use to using mods. If you like being able to configure things to the max however then this is the mod for you.

 This addon was created to provide visual cues (auras) when you gain buffs, debuffs and many more. Very useful for shorts buffs or debuffs, it allows you to draw in the center of the screen, or around your character, very customizable visual effects, rather than having to look at or mouseover buff/debuff icons/actionbars.

Initially created to give visual cues for short duration procs like “clear casting” or some boost trinket you activate, many more aura triggers have been added since.
It now works with debuffs (whatever their name), debuff types (like Magic or Curse), combo points, harmful area spells, weapon enchants, Health, Mana, Rage or Energy thresholds, action cooldowns, aggro, pvp status and stance or shapeshift form.

Event Alert

This mod acomplishes pretty much the same thing but the procs are preset for each class, the config is pretty simple and easy to use. If you don’t like to be bothered by a lot of configuration then this is what your looking for.

 The addon will notify you in the middle of your screen with an icon, name of the spell that has procced, the time left on the proc and will make a subtle sound. EventAlert is also able to handle more than one proc at a time (this option was not available in previous versions).

I am not fond of addons that have very complicated installation and setups. The mod should work on install without any config, but if you wish to change any options use the following command: /ea options