Doing some trial and error :( on a linode.
I've tried tightvnc but get a grey screen with the identical setup I used to use with 12.04. I ran with 12.04 and tightvnc successfully for about 2 years.
I have an outstanding bug reported for x2go and 12.04 so I'm hesitant to use it with 14.04. The bug is unacceptably slow performance after a few hours of use. This is x2go bug # 465.
I considered nomachine's free edition but their website says that "the free NoMachine 4 is designed to work the same across Windows, Mac and Linux and give users access to the physical desktop of the remote computer. If you need to create virtual desktops on demand, want to limit the logins to SSH, or are using NIS, Kerberos or other enterprise server functionalities, you need one of the NoMachine Enterprise server products". If my understanding is correct, a cloud server from linode has no physical desktop provided to the customer so nomachine is recommending the paid-for product.
I tried x11vnc but have not succeeded and I have an unanswered problem for this method.
My question for x11vnc and 14.04. x11vnc might also need a physical display.