raiding addons that everyone must have

Just search these addons on google, they're not hard to find.

Everyone
Deadly Boss Mods or BigWigs Bossmods
The above mods will notify you of important events during the fight (such as the bug swarm on the first boss of the arachnid quarter in naxxramas) and having one of these is mandatory for raiding.

Tanks and DPS
Omen Threat Meter or Skada Damage/Threat Meter Combined
Shows how much total threat the raid members have on the targeted mob. DPS must know how much threat they have relative to the tank so they don't pull aggro. If you are a dpser and you think you don't need this, you're wrong.

Healers
Healbot or Grid + Clique
It's not impossible to heal without these addons, but you will unquestionably be a more effective healer once you have these addons figured out. While these are mandatory for healers, they are recommended for tanks and DPS as well. Any ability that you can cast on a fellow raid member to help out is made easier with these addons.

Optional

IceHUD
This will put your health and mana bars in a vertical curve on either side of your character so they are much easier to monitor during the fight without moving your eyes far away from the boss. See here.

Bartender
Allows for easy arrangement of your action bars. You can move them anywhere on your screen and make them bigger or smaller. Also allows you to set your keybindings easier.

Recount Damage/Healing Meter
Same as omen except measures DPS or HPS for the raid instead of threat (might be able to do threat as well, not sure).

Elkano's Buffbars
Displays your buffs/debuffs in a more meaningful way. Can display the name of the buff without mousing over the icon, and displays exactly how much time is left before the buff runs out.

OmniCC
Shows a countdown on your action bars for abilities that are on cooldown, so you can see exactly when your abilities will be ready for use again. Great for classes with complex ability rotations. Recommended for everyone.

Quartz Casting Bars
Makes your casting bars and the enemies casting bars more visible. Also includes a slim bar for the global cooldown to help time your rotation better.

MikScrollingBattleText
Shows damaging and healing abilities used on you in scrolling text on the lefthand side of your character, and shows damaging and healing abilities used by you on the current mob in scrolling text on the righthand side of your character.
or Parrot
Another scrolling battle text addon (ty Asa).

PallyPower
Great addon for palladins to manage their buffs in groups or raids. Pally only =(

PitBull Unit Frames
Makes your unit frames customizable and repositionable.

Atlas
Tells you where to go in the instance!

Personally I prefer Parrot for my floating combat text, but that's just me. damage output on right, damage you/pet takes on left.

[Edit: =P Easy! -Asa]

Know where you can get the bundle of this? A zip file would be cool for us lazy folks!