WordPress is a great content management system to use to build blogs and social networks. It already has everything you need to get started. If you are building a social network or planning to accept new users in your community, you may want to consider adding enhanced profiles to your site. UserPro can help with that. It adds beautiful front-end profiles to your site and enhances your communities in various ways.
UserPro is designed for growing communities. It adds attractive front-end user profiles and supports unlimited custom fields. Users can upload files from the front-end. The plugin provides support for reCAPTCHA. You do have the option to verify certain profiles like Twitter and other social networks do. The script also takes care of creating member lists for you. Advanced member sorting and filtering are available.
UserPro is easy to customize and gives you a ton of options to enhance your community. Might be an overkill for simple blogs but could work great for growing social networks.