You probably already have materials such as brochures on "What to Do When You're First Diagnosed With..." or "A List of Legislators to Write to About..." Those materials should be made into your first web pages. After that, get your service providers -- nurses, social workers, lawyers, pastors -- to write monthly articles or stories.
If you have your website set up by a developer, make sure they provide you with an easily updateable form to create your own pages on an ongoing basis. If you have no budget or expertise for creating web pages, set up a blog and link to it from your site. Blogs are free and easy to use
The same form you use to upload articles can also be used for news stories. If you don't have the staff to write stories, you can link to other websites that carry relevant news about the latest Federal Budget Cutback, legislation or medical discovery related to your cause.
There are sites such as Calendars.net which will host your calendar of events. Some are free. Others charge a small fee. Usually you can customize the calendar's appearance to blend with the rest of your site. It is then your responsibility to keep it up to date.
If your organization has several local offices, here's a good deal: Free DealerLocater.com will provide you with a free local office locator. Visitor to your site puts in her ZIPcode and a window opens with a list of nearby offices and a link to a map. No ads except a small "brought to you by" acknowledgement.
You don't need a lot of unique material. Just link to the new material on your site with little teaser paragraphs. Newsletters are very good for reminding people of upcoming events.
If you give your clients or donors a choice of receiving the newsletter online instead of in the mail, you can even save on postage.
Forums, also known as bulleting boards or Message Boards, are sites where people can post messages to be read and replied to by other people. They can be a very effective tool for sites devoted to a disease, religious sites, or political sites. Not only are you providing a real service to people who can offer each other online support and advice, you are demonstrating to every visitor to your website that you are a provider of helpful services.
Some web hosts provide free forums as part of their web hosting fee. There are also free websites such as MyIkonboard that will host a forum for you. If you are willing to put up with an ad or two, they're free. Otherwise there's a small fee. Be sure you put a legal disclaimer up, noting that the people dispensing advice to each other are not necessarily experts and not your employees. Also, be sure there are enough people interested in your cause that you will get messages posted. An empty forum is embarassing to the webmaster.
It's also essential to have someone moderating the forum. You want to patrol for spam and for inappropriate material.
As long as your links open in a separate window, thus keeping your site open, you can afford to be magnanimous about suggesting helpful sites. For example, a website devoted to children's issues might link to the local schools or to high quality children's sites such as Sesame Street on the PBS website. (For you techies, the way to make a link open in a new window is to add the parameter "target=_blank" to the link tag.)
Reciprocal links can be a way to build traffic to your site. For more, see Getting Traffic.