Remote access to linux machines with x2go.

Problem; 

You have a linux desktop somewhere, and you're not there.  It's running a GUI application (like firefox or matlab), how do you access it; with the following criteria;

1. Easy to use.
2. Client available for Windows, OSX, Linux.
3. Able to resume previous sessions.
4. Free.
5. Feature rich
6. Backed by an active open source community.

Answer(s);

In order of preference, 1 being most preferable;

1. Use x2go.  An open source fork of NX and my new favorite.
   Fast.
   simple.
   powerful.
2. Use freeNX-server
   It might be ok, but i had issues getting it to work
3. Run VNC over an (encrypted) ssh tunnel
   slow over high latency networks
   complex to setup for novice users.
4. Install VNC with vnc4server
   slow over high latency networks
   pretty insecure, you ought to encrypt that traffic.
5. Use X forwarding over SSH
   very slow
   OSX and Windows clients require an X server install
   complex.
6. Use nomachine NX
   Once the poster-child for linux remote access, now gone proprietary.  Noted here for completeness.

Summary

x2go.  My new goto toy for quick and simple remote access to linux machines.