Here are a few links that you may or may not find useful.
Warcrafter Gives you a break down of your gear and abilities
IMBA : Character Auditor: Gives some advice as to character improvements
Wow Heroes Simplifed Gear List
Wowprogress A very useful resource!
RepCal Wow reputation calculator – how many runs to get those reputation rewards
Gankbang Stats comparison – being updated for Cataclysm
Loot Rank Rank your loot
Warcraft Realms Gives you a complete guild history
Pugchecker Displays the Instance history of players
Wow Tabards – Tabards
Warcraft Mounts – All the mounts
Petopia – Pets
Wow Wiki – Wow! Its a wiki!
wowpedia.org – Merging of Curse and wowwiki
Thottbot – Quest and general information
Wowhead – Just about everything you ever needed to know regarding WoW
Boss Killers – Boss strategy and Information
Tankspot – Boss strategy
Elitistjerks – More theory-crafting than you can shake a spreadsheet at!
Curse.com – Addons
Shadowpriest.com – for all things shadow
plusheal.com – for all other priestly bits and pieces
Additional Useful Files – for specific encounters
Lich King Addons – A pack of helpful tools for ICC
