A&E's Law & Order Boards
Comments
Programming
Characters
Episodes
Michael's Law & Order Message Board
MysteryNet.Com/Law & Order Board
Law & Order Community on Excite
MysteryNet.Com/Cop Shows/Law & Order Board
Messagecentral Law & Order Board
MysteryNet.Com/Courtroom Dramas/Law & Order Board
Complete Law & Order Database's Discussion Board
Mysteries.Com Law & Order Board
Occasionally the direct link above works funny, so you could also go to the Mysteries.Com Messageboard Index, then click on "Television_Shows", then click on "Law_&_Order" and there you are.
Yahoo: Alternate Universe Law & Order Fanfiction Club
Yahoo Law & Order Message Board