LootDB EQ2I EQ2 Flames EQ2 Traders Corner EQ2 forums
MMOUI can be directly accessed from here so I won't link it, same with the Allas wiki.
This is pretty much a complete list, aside from the class specific sites. Although most of the class specific information can be found in the EQ2Flames forums, since the majority of the class specific websites aren't being supported any more. Also, TenTonHammer has shown it's true colors as a hype website on several occasions. If it isn't the great new thing, the content is quickly abandoned and becomes outdated.
EQ2I and Allas EQ2 wiki will have pretty much anything you're looking for as far as quests and general info. EQ2 Traders will cover everything TS related and EQ2Flames will cover the rest. With LootDB filling in item info on the odd drop, you have pretty much everything covered.