Shows you a friends online widget and a page. This component will work only on OSSN 6.6 I don't have time to check on previous versions. If your OssnChat is switched off let me quote a issue here explained by Micahel

https://www.opensource-socialnetwork.org/discussion/view/6407/who-among-my-friends-is-online

Still one thing you should be aware of is that the member-activity update intervals are longer when OssnChat is disabled. Thus, by chance you may pick a member who is still marked as being online but has logged off already.