I believe both games do have multiplayer.

(You should mention which game you are asking about in the title or post.)

Maybe this list of NWN/NWN 2 servers will help you. http://www.nwnlist.com/#

Yes they both have multiplayer - including dedicated server tools to host your own games. My group is currently running a weekly co-op game of the first game.

How is that you are doing that? We and a friend are trying to play the campaign together, but besides problem connecting (still I believe she is not port forwarding), I'm wondering how you are supposed to "save" or "load" :/

I have been using the dedicated server tool. It autosaves every 10 minutes, although I have also manually saved during play before tough battles. You obviously have to let it through the firewall and port forward for it to work. You can even get it listed by using the client extender and modifying your hosts file.

Useful Links:
http://www.neverwinternights.info/dedicatedserver.htm
http://www.neverwinternights.info/nwncx.htm