I've been long years enjoying NoMachine's in form of FreeNX project. FreeNX project is almost not maintained and even NX Server Free edition (binary closed-source distribution from NoMachine) does not work well with modern desktop environments like KDE 4.x.
My bottom line is that I've wanted NX-like desktop sharing in terms of performance but without a headache of building sources based on Xorg makefiles from 5 years ago and hunting FreeNX bugs.
And there is an elegant solution to my quest: x2go. It has packages for Ubuntu and RedHat so I was up and running within minutes. It also provided KDE plasmoid. Moreover, their desktop client is far more rich than NX one and does not look like 10 years old software :)
Here is another blog post regarding x2go: http://googlefodder.blogspot.co.il/2012/09/nomachine-nx-freenx-neatx-which-should.html