I've pulled up an old list, from way back when, and copied it below. I'm sure most of the stuff is out of date, but if anyone has anything to add, I'd love to hear from you.
I know Haze has gone under. If anyone has any further info on other worlds, or these ones listed (such as how similar they are to us), I'd love to hear!Tales of the Moonsea
http://www.talesofmoonsea.net/forum/index.php
General Description
TBC
Platform
NWN1
Relative Size
<20 players/ 13 DMs
Number of Servers
1
What Makes It Unique?
Active, friendly community. Good DM response time on forums.
Exodus
http://www.exodus-world.com/
General Description
Sister community to ALFA. Alike in most ways with a smaller playerbase
Platform
NWN2
Relative Size
~20 players/ ~6 DMs
Number of Servers
1
What Makes It Unique?
Skullport and Undermountain
http://dmg.kalusia.com/dmg/e107_plugins/forum/forum.php
General Description
Underdark servers
Platform
NWN2
Relative Size
~30 players/ ~4 DMs
Number of Servers
2
What Makes It Unique?
Pure underdark setting in a roleplay environment.
Avlis
http://wiki2.avlis.org/Avlis_2_Wiki
General Description
Massive, established roleplay worlds
Platform
NWN1 & NWN2
Relative Size
100+ players/ ALFA sized staff
Number of Servers
11 NWN servers, 1 NWN2 server
What Makes It Unique?
Size, respect, design team.
Haze
http://www.nwn2haze.com
General Description
NWN2 Haze is poised to be the defining element in hardcore roleplay for Neverwinter Nights 2. As a re-imagining of the Hall of Fame awarded Haze, developed by members of the same team and with an additional two years of experience, it will deliver the same strictly enforced high-impact, high-intensity Forgotten Realms roleplay experience.
Employing permanent death and a huge number of custom systems and tweaks, NWN2 Haze offers a whole new kind of gritty, immersive, edge-of-your-seat roleplay that other servers can't deliver. Through a talented team of Dungeon Masters and bold ideas, NWN2 Haze is a world that rewards good roleplay with great fun, and gives characters the opportunity to conquer or fall by their own actions.
Platform
NWN2(MoTB) - Currently in Open Beta
Relative Size
Currently list 550 registered players, I was seeing ~20 on the server during evenings EST.
Number of Servers
1
What Makes It Unique?
They are very much dedicated to putting roleplay ahead of everything else. Level progression is slow and caps at 5. Immersion and persistency are design features. They have carved themselves a very unique setting as all players begin by being washed ashore on a mysterious island and start over from scratch, no matter what their character's background. My description is not doing them justice, so best to check their website as they have crafted their phrases thoughtfully.