My home network includes a Linux (Centos) server. The server is headless, so any GUI-based maintenance is carried out via VNC. From a Mac, I always thought that meant 3rd part software for a VNC client. There's a few available, been using them a few years, but none that I liked that much. And now I just discovered - OS X has its own built in VNC client...
From finder, pull down 'connect to server', and specify it as something like: vnc://servername:5901 , modified for your 'servername' and port number, of course. Following password requirements up pops OS X screen sharing with, in my case, the Centos GUI desktop in all its glory. Same can be done from Safari, just type the vnc:// address into the bar.
Apol's if I am the only person to whom this is news. Things that are obvious to other people are not always obvious to me.