Here are some alternatives to Ning that you can use to organize your own social network.
CubeTree is a free service designed for companies that would like to build a social network of wikis, shared items, and microblogs for their employees. On CubeTree anyone can create a network and invite colleagues. All colleagues must have the same email domain. For example, if I wanted to create a network, only people with an @freetech4teachers.com domain could be in my network. Everyone in the network can create a profile (Facebook-like), post updates, share documents, collaborate on documents and spreadsheets, and share items from their RSS feeds. The video below offers an overview of CubeTree's offerings.
Jabbster is a free service that allows families and groups to create private online communication networks. Within your private network you can host discussion boards, share photos, post an event calendar, and share bookmarks. Setting up a Jabbster group is quick and easy. Simply register for an account, name your group, and send invitations to the people you want in the group. If you create the group, you are the group administrator and can delete any content or user from the group at any time.
ShoutEm allows you to make your own public or private network. As the administrator of your own network you can restrict access to only those people you invite. You can also exclude entire email domains in the adminstrative settings. Your ShoutEm network can be as simple as Twitter or as robust as FriendFeed. As the administrator of your ShoutEm network you can choose to allow users to post pictures, attachments, and have threaded conversations. The video below provides a quick overview of ShoutEm.
Edmodo is a microblogging system designed specifically for teachers and students. Using Edmodo teachers can create a microblogging network for their classes. Edmodo allows teachers to create a group specifically for their students and exclude those not invited to the group. Edmodo provides teachers with a place to post assignment reminders, build an event calendar, and post messages to the group. Just as with any good microblogging service users can share links, videos, and images.
Learn more about Edmodo in the video below.