1) "The Vault" http://nwvault.ign.com Neverwinter Vault is the BEST all around Neverwinter Nights related site. It is my home page. I must check it out 5 -10 times a day. Maximus does an awesome job keeping the community up to date with what's going on.
2) "A land Far Away" http://www.alandfaraway.net/ this site is attempting to setup as many servers as possible in order to recreate The Forgotten Realms.
3) "Neverwinter Connections" http://www.neverwinterconnections.com/ Looking for a place to host your mod? Looking to join up with like-minded individuals? Check this site out!
4) "Neverwinter Haven" http://neverwinterhaven.com/ Just a good all around Neverwinter Nights site.
5) "Ladies of Neverwinter" http://www.ladiesofneverwinter.com/ My wife would be very despondent if I failed to mention this site. This site as the name implies is dedicated to bringing the women playing CRPGs to the main stream.
Other Fantastic Neverwinter Nights Sites, in no particular order.
http://www.neverwinternexus.net/
http://www.norworld.cncdsl.com/
http://www.reapers.org/nwn/reference/
http://www.whitetowergames.com/
http://www.mystaranet.com/~vulcano/index.html