One of my favorite Joomla! components is the Community Builder by Joomlapolis. I used it in the LancasterSuites website, where I incorporated a Simple Machines Forum engine to the website. Aside from having extended user profiles, this component merges the user profiles of the forum to the users of the website, thus enabling a single log-on profile for the entire website.
You can visit and explore the website as well as click on links specially the Adsense links on the right side of the page. 😀
You can also visit the home of Community Builder for a more detailed explanation of the component’s features.