The Federation of American Scientists has set up a Wiki whose purpose is to create an almanac of virtual worlds. As stated on the site:

“This is a project to create a free, complete, up-to-date, and reliable guide to virtual worlds. So far we have 76 entries on virtual worlds written and edited by people from around the globe. Check out the Help page to see how you can edit any page right now or the Project page for more information about us and getting involved. Please note that this wiki is semantic-enabled and uses various properties and templates that make editing easy and uniform. Please see our Introduction to learn how this wiki is different than most. “

The site has a workable list of virtual worlds but needs content. Head over and pick a world or two and help.