Here are mine:
1. Titan Panel - Newest version works great with WotLK
Desc.: Titan Panel adds a control panel bar on the top and/or bottom of the screen and allows a framework for extensive plugin support. Some features included are XP tracking, Ammo, Bag, Clock, Coords, GoldTracker, ItemBonuses (w/BonusScanner), LootType, Performance, Regen, and Repair.
2. Gatherer - Newest version works great with WotLK
Desc.: This Addon keeps track of what you Gather or Farm. The addon does not track like a tracking ability does, rather it "remembers" where you have found various items in the past. It does this whenever you gather (perform herbalism, mining or opening) on an item, and records the specific map location in its history. You can import and export your data between characters... As in I can send to and receive from Hayden.
3. WHDB - Newest version works great with WotLK
Desc.:
WHDB is a quest info database that integrates into your quest log, provides location and drop info for monsters and item objectives and quest comments.
WHDB can plot notes with objective locations into the map if you are using one of these addons: [OPTIONAL]
* Cartographer (recomended)
* Metamap
* MapNotes.
We know what the next two are.
4. QuestHelper-0.93 - Seems to be working well with WotLK
5. Cartographer 3 - Seems to be working well with WotLK