Besides all the professional NX servers for enteprises, NoMachine also offers a free (as in beer) server, which offers most of the features available in the other servers (with a maximum of 2 simultaneous connections). If you’d like to discover how NoMachine’s servers work or are configured, give it a try! You may find the fonts to have a slightly different look compared to freenx.
Now that their latest maintenance release fixed a QA problem in the tarballs, ebuilds for this server will get into portage soon (net-misc/nxnode and net-misc/nxserver-freeedition, already available in the NX overlay). They will be available for x86 and multilib-amd64
Note for people who already have it installed: if you encounter license problems, the quickiest way is to remove your /usr/NX folder, and reinstall it entirely. Despite being free, this server still needs a license file, which may get clobbered by previous installs