CT-Raid-Assist
Background: http://www.curse-gaming.com/mod.php?addid=694
Summary: This is the new addon for raid helpers. Make it mandatory for the guild!!!!!
CQ-ManaConserve
Background: http://conquest.teamgbu.com/viewtopic.php?t=107
Direct Download: http://conquest.teamgbu.com/download.php?id=35
My Summary: Cancels your heal mid-cast if your target passes a certain threshold in HP so you don't WASTE MANA. This is pretty much vital for raids when you have healing rotations with 5-6 healers healing the same target. Pre-emptive healing should no longer be a mana-gamble. If you're aren't pre-emptively healing to begin with, WTF ??
CQ-Cure
Background: http://conquest.teamgbu.com/viewtopic.php?t=167
Direct Download: http://conquest.teamgbu.com/download.php?id=36
My Summary: Makes dispelling/cure poison/cure disease a no-brainer. The less time you spend staring at debuffs, the more time you can spend staring at healthbars. Don't overly rely on it (i.e. don't replace the dispel button on your quickbar with it), but spam it when fighting Garr or Baron Geddon when you have to mass dispel.. makes it easier and again 1 less thing to worry about. When you need to dispel the normal way, just select the guy using F-keys, then cast your normal dispel.
DruidBar (for Druids)
http://www.curse-gaming.com/mod.php?addid=251
Weeee... this bar shows you your mana in cat/bear form =)
LootLink
Screenshot: http://www.curse-gaming.com/modscreens.php?id=94
Link: http://www.curse-gaming.com/mod.php?addid=130
Summary: This is a sweet mod that saves every item you come across into a searchable database, so you can check it out later. You can even link any item in this database to chat windows and stuff as if you had it in your inventory

Links to UI Enhancements:
Ultimate UI
Screenshot (customizable): http://www.curse-gaming.com/modscreens.php?id=1027
Link: http://www.curse-gaming.com/mod.php?addid=478
Summary: This is another one of those all-in-one interface packages. Quite popular these days.
Gypsy Mod
Screenshot: http://www.curse-gaming.com/modscreens.php?id=356
Link: http://www.curse-gaming.com/mod.php?addid=320
Summary: This mod essentially makes everything in your UI moveable. A lot of my guildies use it.
Flex Bar
Screenshot: http://www.curse-gaming.com/modscreens.php?id=12
Info: http://therealorang.com/download/FlexBarHelp.htm
This is a barebones UI mod which adds tons of buttons, and allows you to move them around. Read instructions please!
Nurfed UI
Screenshot: http://www.curse-gaming.com/modscreens.php?id=702
Information: http://www.curse-gaming.com/mod.php?addid=298
This is the newest UI which people seem to be abandoning Cosmos for.
CTMod
Screenshot: http://www.curse-gaming.com/modscreens.php?id=284
Information: http://www.curse-gaming.com/mod.php?addid=273
The original Cosmos replacer, it isn't as jammed packed with stuff as Nurfed or Cosmos is, but gives the additional buttons.
Cosmos UI - (kinda broken with the last patch... Cosmos 2.0 is coming out in a few weeks, hopefully will be better)
http://www.cosmosui.org/cosmos/
This is the grand-daddy of UI suites. I still use it, others have moved on to cleaner/better interfaces. This thing is huge, and will inevitably install lots of mods you'll never turn on, but if you don't know what you want to begin with this is a great mod.
-Courtesy of Eirene
Macros for Dispel/Cure Disease/Cure Poison/Cure Curse
(these cure the last person who sent you a tell)
http://www.e.kth.se/~e95_ima/priest.txt
http://www.e.kth.se/~e95_ima/shaman.txt
http://www.e.kth.se/~e95_ima/mage.txt
-- Old and retired
RaidBar (abandonware--use CT Raid Assist now!!!)
Background: http://www.curse-gaming.com/mod.php?addid=330
Direct Download: http://www.curse-gaming.com/mod.php?downid=1708
My Summary: This is the big daddy of helper-mods. Don't do a raid without it. It's especially helpful if you know you'll be raiding with weaker players or if you're short on healers (which BWC is on both counts hehe).