Besides the megaplugin BuddyPress and its bestial integration that converts WordPress into a complete social network we recently saw that there is another system to do practically the same thing, on that occasion with some lack , with Mingle . Well, they are not the only options for having a social network with WordPress.
WP Symposium is a plugin that also adds social network functions to WordPress and that, like Mingle, you can also improve with other specific plugins for the, how Toolbar to manage the social bar or Blog post to have a blog dedicated to your social network.
Then, in addition to the ] free version and GPL you can add payment options that carry your functionalities to infinity.
The counterpart of WP Symposium versus Mingle is that hasthat configure that intimidates something at the beginning also lacking a simple assistant like BuddyPress, but its possibilities are huge so it's an option that you should not rule out.