I ran across this blog post at WPdesigner.com on using the WordPress blog software to run a membership directory.
It points out some useful plugins and work arounds.
WordPress is a great blogging platform and can be used as a content management system for other types of sites as well. I’ve used it to build several none blog sites for clients and it works well.
With all the themes, plugins and modifications available for WordPress, this is worth checking out for your site.