Materia Magica
The source of all the fun.
The Cwn Annwn
The latest and now greatest info site. Includes player stats not available elsewhere.
Knights of Chaos
Older site, has some great guides and mark info not found elsewhere.
An allied clan. Includes a great collection of maps and an awesome PG guide.
Lantis' Site
Great little site run by Lantis which has run logs and mark info you can't find elsewhere.
The Alyrian Wharf
Must have reference for all you ship captains!
Ardant's Atlas
Searchable map for crystal hunters.
Auction Database
Mercenaries of War's Auction Database. (AO is down -Jan 2012)

Link to
Link Graphic #1
Link Graphic #2