No Machine’s NX Server software is another one of those absolutely brilliant finds! This allows RDP type connections to Ubuntu boxes. For the simplest instructions on how to set it up for Hardy, check out Urban Puddle.
EDIT: Updated instructions are available here. On 10.04, it’s as simple as typing:
sudo apt-get install python-software-properties && sudo add-apt-repository ppa:freenx-team sudo apt-get update sudo apt-get install neatx-server