If you have suggestions to add to the list feel free to message or mail aradune.Marcone in game.

ZAMEverquest allakhazam database. Reccommend running an ad-blocker or paying for premium. Otherwise you are going to have a bad time.
Good's MapsBest maps I've come accross.
Brewall MapsDecent maps.
Mapfiend MapsBasic maps sometimes they work.
Zone Connection Map (Velious)Everquest zone connection map up to and including Velious. Courtesy of P1999.
Zone Connection Map (HoT)Old zone connection map up to House of Thule. Made originally by Samanna.
EQ InterfaceEverquest user interface list/downloads. Personal favorite is Savok's Vert.
Everquest TLP ForumsDBG forums, good luck.
EverQuest Official DiscordBeware of trolls.
Xanadas Progression Spell ListNice site for early expansions to find spells.
EQItemsPretty useful site that can give you item choices based on your current gear or when looking for best in slot items. As a warning it's item rankings can sometimes be out of wack, but still nice info.
RaidlootAnother item database.
P1999 wikiNot 100% accurate for live but can glean some useful information especially with reguards to Plane of Sky.
EQTradersTradeskill database. Some things can't be made in early eras but still an invaluable tool.
Almar's GuidesSome of his content isn't for progression servers, but the tradeskill guides can be pretty useful.