Darkness over Daggerford used to be a bioware premium module ( made by pro that got paid to do it and you had to buy the module when it came out at first but it is free now).
here the address:
http://nwvault.ign.com/View.php?view=Modules.Detail&id=5122 if you played Eye of the Beholder 1 from Westwood studion that came out in 1991 then you might want to try the remake by Wolfspirit ( he/she tried to make it like the original with all the good and bad thing).
here the address :
http://nwvault.ign.com/View.php?view=Modules.Detail&id=4029 But there is also the one from Rick Francis and teh EOB team, this 1 use the same lvl design of the original but it was made to be better and more challenging, this 1 got some HUGE hak pack to go with it but it look really amazing.
Here the address :
http://nwvault.ign.com/View.php?view=Modules.Detail&id=4028 And if your are a real fan of EOB like me, get both.
Also go join a nice online PW (persistent world) to play with other because no single player module can beat that. here the link for the top list on nwn vault:
http://nwvault.ign.com/fms/TopRated.php?content=gameworld Most of them will have a web page with information about the world so read before you join, because some allow or forbid class, some need many hak pack to download and install, some allow or forbid PvP (player versus player) and lot more stuff, so reading about the world first is essensial IMHO (in my humble opinion).
Module that are part of a serie are normaly of higher quality because of the time investement needed to make them so you could check those out too.
and if you feel like playing the really bad guy in single player module check the Blackguard serie 1 to 3.
hope you enjoy my selection and advice.
bye and have fun.