I have gifted them several times because they are favorites. I got tired of retyping the same list of links to pm everyone so I am consolidating it here. I hope this is helpful.

First off, NWN1:

Request multiplayer keys from GOG support first. (On the website, select the support tab, then the Contact Us tab under that, tick the radio button marked Other, select multiplayer key request from the pull down menu. Submit a subject and message politely requesting multiplayer keys for Neverwinter Nights Diamond Edition. An email reply with the keys should appear in your inbox shortly.) Copy the nwncdkey.ini file from the archive attachment in the support email into your Neverwinter Nights Diamond directory, allowing it to overwrite the old one. Then run the premium modules re-installer found in the game extras for the Kingmaker EP modules to work with the new cd-keys you just put in.

Then, if you like having a complete package, use the links in the solution on this thread to get the additional Premium Modules: [url=http://en.wikipedia.org/wiki/Neverwinter_Nights:_Pirates_of_the_Sword_Coast]Pirates of the Sword Coast[/url], [url=http://en.wikipedia.org/wiki/Neverwinter_Nights:_Infinite_Dungeons]Infinite Dungeons[/url], and [url=http://en.wikipedia.org/wiki/Neverwinter_Nights:_Wyvern_Crown_of_Cormyr]Wyvern Crown of Cormyr.[/url]

You just want the installers for Pirates of the Sword Coast, Infinite Dungeons, and Wyvern Crown of Cormyr. Do not bother with the others, as they are already part of the Diamond Edition/Kingmaker Expansion. Since the master servers are all down, the Premium Modules work regardless of cd-key.

There are also three Post Premium Modules that were started as Premium Modules, but were released for free on the vault when the Premium Module program was canceled:

Tyrants of the Moonsea

Darkness Over Daggerford - by Ossian, the same studio that produced Mysteries of Westgate for NWN2

Hex Coda - I skipped this one myself because it isn't a D&D setting, but it was a Post Premium Module.

I'll add here that just because I have linked to official and semi-official content only, by no means do I wish to imply that it is the best or only content. I can't even begin to recommend the best community made modules, as there are so, so many. Look through The Neverwinter Nights Vault Hall of Fame for Modules.*Dead Link Removed. IGN has dropped The Neverwinter Nights Vault and a community site, The Neverwinter Vault is working to preserve the IGN site's content. Unfortunately, there Is no Hall of Fame there and search filters/site organization are a bit lacking compared to the old IGN site. I am in contact with the site administration in hopes of remedying this.

Check out these forum threads if you are having issues with stuttering/low framerates (switch to Miles 2D sound) or (rename the exe.) It has also been recommended on several forums that the game be run in Windows XP SP2 compatibility mode. If the cinematics do not play, you may need a Bink dll file in the NWN directory or you may need to turn on Safe Movie in the .ini file, as both are described in [url=http://www.gog.com/forum/neverwinter_nights_series/campaign_videos_cutscenes_not_playing_right/post5]this thread.

As far as servers, I highly recommend these:

Arbor Falls - Arbor falls requires some installation but the content is well worth it. Follow the instructions on the vault page to get all of the requirements as well as Lord of Worms' own content. *Direct connect to the server at 74.76.208.87:5121.
Even though a camera mod is listed as optional you should get one, but due to the trojan mentioned in the comments for this one, I am going to recommend the Higher Ground version of the exe or [url=http://dl.dropbox.com/u/4088244/nwnchange/nwmain-169-hg-CD-FIXs.zip]here. It really improves the game on any server AND singleplayer. Changing the name of these back to just nwnmain.exe should fix driver related bugs like invisible characters. Back up/rename your original exe first.

Higher Ground - For the higher ground servers you just need the CEP.

Worldtraveller also recommends Greyhawk Lords 2 and Cormyr-Dalelands. I've not tried them yet.

If you wish to override models of some player character parts, there are improved hands and improved bodies for humans. You may want to exclude the two head files in the hands download. *These are dead IGN links, I have not seen these up yet on The (current) Neverwinter Vault. When I do I'll update these.

The gamespy servers that list the independently run game servers are down, but the game servers themselves are up because any player that wants to run one can! You can search the web and do a direct connect to the server's IP, or you can try this Client Extender, though I have not been able to get it to work on my system. (Note: The patching option for the client extender includes a camera mod and requires that you patch an unmodified exe, so if you want to try the extender with the patch option, I would do so before applying the camera mod. If you have already applied the camera mod and did not keep a backup of the original exe, there is a launcher option that doesn't require patching.)

NWN2:

Setting up multiplayer should just be a matter of running the key changer utility (SerialTool.exe) in the Neverwinter Nights 2 directory, using the keys on your game page. Neverwinter Nights 2 uses an autodownloader, so any server you log onto will automatically give you the custom content files it uses, nothing to really set up in advance. Still, if you want some goodies to play with offline there are plenty on The Neverwinter Vault.

The gamespy servers that listed the independently run game servers are down, but the game servers themselves are up because any player that wants to run one can! The[url= http://social.bioware.com/forum/Neverwinter-Nights-2/NwN-2-Persistent-Worlds-amp-Multiplayer/Announcing-the-NW N2-Client-Extension-client-crash-fixes--enhancements-3116438-1.html] NWN2 Client Extension[/url] not only does a great job replacing the gamespy servers but also fixes other bugs and crashes. I highly recommend all players install it. With the GOG version, you must run the NWN2 updater (nwupdate.exe in the game's directory) once before installing the Client Extension.

It is likely that you will want to adjust camera settings to be more similar to NWN1 and/or simply more usable.

As user __doug__ tells us, we can avoid sitting through the movies every time we start the game:

"In the nwn2.ini file in the "Documents\Neverwinter Nights 2" directory, add the line "Disable Intro Movies=1" in the "[Display Options]" section."

Sadly, though the official campaigns are excellent, it is much harder to find good servers/modules for NWN2 than for NWN1. The tools provided by Obsidian were just not as friendly to builders as Bioware's. Many, many scripting functions that were released throughout the course of NWN's updates were just never ported to NWN2.

Fans of Baldur's Gate who would like to try the game in an updated engine should check out the Baldur's Gate Reloaded mod for NWN2.

If you are knowledgeable about these games and feel that I have left out something essential, please post or PM me and I will continue to update this.

This certainly looks usefull to someone like me who has no idea what he's doing. I'm gonna take my time and check those, even though I usually don't care about multiplayer in RPGs. +1!

Multiplayer is definitely the highlight of NWN1 (and 2 as well for some.) Arbor Falls is just an amazing creation. Pity nobody goes there. I play there alone and still find it more enjoyable than singleplayer modules.

Nice TY for the links!!

+1, for nice recommendations.

Also for more links and recommendations, look at the stickies at the top of the forum.

NWN2 Client Extension is that for all multiplayers or all players in general?

Depending on how Old School (TM) you are, you might want to check out Greyhawk Lords 2. (google the forums, and you can get the connection info there). Disclaimer: I used to be the main admin for that server and am mostly responsible for starting it back up about 4 years ago. There's a solid player base, and during prime time (US), there are usually at least 5-6 players and a DM around.

If you want a much larger player base, with a really well supported server, set in the Forgotten Realms, I highly recommend Cormyr-Dalelands (again, google the forums). Much larger player base, and their DMs and coders are quite sophisticated with lots of neat toys and tricks.

It's for all players. Multiplayers will benefit the most from it, but several fixes (especially in regards to stability) make it a must have for singleplayers too.

thx

Thx for info and links!

Some of the bugs fixed by the client extension affect single player as well, so I recommend it for anyone, but the gamespy list functionality which is probably one of the main selling points for using the extension just affects multiplayer. Doh, I see now that someone answered much faster than I.
Unless this has changed, you need to request a set of unique multiplayer keys (one per expansion) from GOG support in order to play online.

If you look in the directory Neverwinter Nights is installed in, you should see this file, nwncdkey.ini. Open it with a text editor and you will see where it lists the keys. Paste the new numbers over the old ones. In some cases, GOG support might just send you the file, in which case you would just overwrite the old one. Does that help?

Yes greatly thank you I'm sure i can figure it out now lol

Good, I changed the wording a bit and added step by step instructions in the parenthesis.

Thank you for the recommendations, shall I add them to the main post? At the very least, the links are:
Greyhawk Lords 2 and Cormyr-Dalelands.