TTLG Forums -
    These are some of the best forums on the Net to find information on the Thief series.  Very friendly population, flaming is very rare outside of Community Chat.
    If you are interested in editing for Thief, then The Editor's Guild is the place you want to go.

Keep of Metal and Gold -
    A good source of Fan Missions, Tools and Fan Missions on DVDs.  Also the coordinator of the Small Fan Mission Contests.  While he keeps his FM archive fairly updated, this is more of a place for those with slow internet connections that want their FMs on a DVD.  For Downloading FMs see Cheap Thief.

Cheap Thief Missions -
    This is the distribution center for Fan Missions, hosted by Epithumia.  Most authors will upload to CTM directly, and those that don't find their mission the hunt of Epithumia's search engines... making this the most up to date archive of Fan Missions available on the net.