BetterPHP

I'm doing a tutorial series for thenewboston, however I am in need of ideas for features, if possible.

The series is simply put; Facebook.

In more depth, I am basically showing people how to build a social network, almost identical to Facebook basics and so I am in need of any features people would be interested in learning how to make.

Thanks

Avatar / Profile picture upload and management.
Wall posts / Profile comments
Friend System
Private messaging
Groups

These are the ones currently in my head .