I had written a blog post about branding your business through building a Ning community. For the beginner-level website owner, this is still a great option. Recently another option emerged which is by far the best free option for building a community.
BuddyPress.org. This is a plugin for the well known WordPress blog platform that turns your blog into a full social networking platform. Studio98 was recently hired by a client to build a Home Staging Community for them, we did this with BuddyPress. The system is 100% customizable (open source) and coded well for search engine optimization.
The plugin is newer so further developments are still needed, but it has a great base for a start. If someone wants the flexibility, I would definitely recommend BuddyPress over Ning.