With so many big changes in patch 4.0.1 I thought I would create a quick list of some helpful class guides for all classes, rather than people inevitable spamming the guide section with "Blood DK tank guide", "Unholy DK dps guide", "Frost DK dps guide", "Arcane mage dps guide", "Fire mage dps guide"...etc you get the point. It gets messy.
Death Knight:
Death Knight Blood Tanking [Ensidia Guide]
Death Knight Frost DPS [Ensidia Guide]
Death Knight Unholy DPS [Ensidia Guide]
Death Knight Tanking [Pwnwear Guide]
Death Knight - all specs [Deathknightbuilds.com Guide]
Mage:Mage - all specs [Ensidia Guide]
Mage - all specs [Magebuilds.com Guide]
Arcane Mage [Wowphiles Guide]
Arcane Mage [Suite101 Guide]
Paladin:Protection Paladin [Ensidia Guide]
Holy Paladin [WoWPro Guide]
Holy Paladin [Tankspot Guide]
Retribution Paladin [Retributionpaladins.com Guide]
Retribution Paladin [Freewowguide.org Guide]
Druid:Balance Druid [Ensidia Guide]
Restoration Druid [Ensidia Guide]
Restoration Druid [Restokin Guide]
Restoration Druid [Druidlove Guide]
Balance Druid [ElitistJerks Guide]
Balance Druid [DruidDigest Guide]
Feral Tanking [DruidDigest Guide]
Feral Druid [WowInsider Guide]
Warlock:Warlock - all specs [Ensidia Guide]
Demonology Warlock [Zorohon Guide]
Rogue:Rogue - all specs [Ensidia Guide]
Rogue - all specs [TenTonHammer Guide]
Rogue - all specs [PveRogues Guide]
Rogue - all specs [Wow Contender Guide]
Warrior:Warrior - dps specs [Ensidia Guide]
Protection Warrior [Ensidia Guide]
Protection Warrior [Thread Meters Guide]
Fury Warrior [Wow Philes Guide]
Priest:Disc and Holy Priest [Ensidia Guide]
Shadow Priest [Ensidia Guide]
Shadow Priest [Adept Guild Guide]
Holy Priest [Tankspot Guide]
Discipline Priest [Type H for Heals Guide]
Hunter:Hunter - all specs [Ensidia Guide]
Beast Mastery Hunter [Warcraft Hunters Union Guide]
Survival Hunter [Warcraft Hunters Union Guide]
Marksman Hunter [Warcraft Hunters Union Guide]
Shaman:Enhancement Shaman [Ensidia Guide]
Elemental Shaman [Ensidia Guide]
Restoration Shaman [Ensidia Guide]
Restoration Shaman [Totemspot Guide]
Restoration Shaman [Life in Group 5 Guide]
Elemental Shaman [Totemspot Guide]
Enhancement Shaman [Totemspot Guide]
Enhancement Shaman [Myrddin Guide]
If you wish to add a guide to this list that you think it worthy, please let me know.