Community Server is the award winning platform for quickly and easily creating online communities and has all the integrated tools, such as: discussion forums, blogs, photo galleries, file galleries, search, RSS tools, content management, advanced user permissions required for building communities.
Community Server also supports a number of add-ons and gateways that enable additional functionality such as: single sign-on modules, posting to your blog through email, the ability to post and reply to forums through email, and file management tools for easy drag-and-drop management of your file or photo gallery. You can learn more about these add-ons and others at communityserver.org.