Thief Series

The Circle of Stone and Shadow
TTLG produced site which includes news, fiction, utilities and a large archive of fan-missions.
http://www.thief-thecircle.com/

Garrett's Notebook
Includes a walkthrough which reveals the placement of secrets and loot hidden in the Thief 1 and 2 missions.
http://www.3dactionplanet.com/thief/walk

The Keep of Metal and Gold
A collection of fan missions with screen shots.
http://www.keepofmetalandgold.com/

The Keeper Library
Background details, hints and tips about the campaign world.
http://www.btinternet.com/~sneaksiethiefsie/

Lytha.com
Large sections dedicated to the Thief series of games; including FAQ, newbie hints, surveys, detailed walkthroughs, loot lists and general information.
http://www.lytha.com/

Thief Underground
Features articles, media, fan missions, tutorials and dromed resources.
http://www.3dap.com/thief/

Zaccheus - The Honest Thief
Fan missions, links, tips and challenges. Includes dromed advice.
http://www.rclsoftware.org.uk/thief/