Ok, first you need to make sure your host provides a VNC service. 99% will have this feature. If they don't, you can usually use web user interfaces to work within the programs you are accessing remotely..
For a quality connection + functionality, I recommend the following VNC viewers:
For Mac OSX VNC Client, http://www.jinx.de/JollysFastVNC.html
For Windows VNC client, http://www.tightvnc.com/
If you're looking for alternatives to VNC, or simply using a *nix platform, you can use SSH with x tunnelling and then run the application you desire. This basically involves installing an SSH server on a *nix HOST, then connect to it via a command line or terminal window. Assuming you're issuing the correct commands, you have immense power at your fingertips.
No need for rep and thanks. I hope you found this information useful. Let me know if you need anything else and I will gladly assist. Take care