I try to do a variety of things to both attract and keep players. Maybe the following will help other PW admins (especially those newer to the scene) in attracting/keeping players.
â–º I keep a thread on these forums and try to do an update every month just to let potential (and past) players know that development always continues in my PW.
â–º I regularly post a site ad on the front page of the Vault.
â–º I try to keep my website informative, well-organized, and up to date so that players don't have to dig through the forum to find out the latest info on things like classes, spells, feats, systems, and required downloads. I do have a forum (a very active one) where I invite player participation (everything from bug reports to suggestions to completely un-related socializing)...and I try to keep the forum organized so that visitors and regular players alike can find the information they need without too much time or effort.
â–º I listen to player suggestions and feedback for improving my game. I don't always make changes based on those suggestions or feedback, but I read every single one of them. Some I decide right away not to use, some I use parts of, some I use right away, and some I end up using even a year or more later. Player feedback can definitely help shape even an "action" world...right now my players are helping me to develop a custom epic magic system, and their posts are helping to shape the game mechanics in ways that I didn't think of myself.
â–º One thing I do (and having an active forum helps) is to always be completely open and transparent about what I'm doing and planning to do with my PW. Players know about upcoming changes. I try to explain my reasoning when I make changes or updates. I let players know if/when real life is going to interrupt my plans (and with infant twins, my players have been very understanding of the fact that a wife and kids take time). I have several very helpful and resourceful DMs that work with me to help out players when I'm not online myself. I do my best to treat all of my players fairly and equally. And my players should know even before they ever log in for the first time that I am easy-going and I see my PW as a creative hobby and not something that has to be serious 100% of the time.
â–º As far as action vs. role play, I try to strike a balance that mirrors my pen-and-paper D&D games. A casual game where nobody is forced to be deep into role-play of their characters, with plenty of action to keep folks busy. I have nothing against role-play at all, leaving it up to players to initiate and go with...it's not enforced. This style may not suite all PW admins, and I don't think it should...each PW should have it's own style and atmosphere.
In the end, I think that players will move from server to server until they find a game world they enjoy spending time in. I know I have several players that never play anywhere else, and I have several players that play in my PW sometimes and sometimes in others. As long as they are having fun playing NWN, even if it's not my particular PW, I'm happy.