SSVNC adds encryption security to VNC. It provides a GUI for Windows, MacOSX, and Unix that automatically starts up an SSL or SSHtunnel for connections to any VNC server. It also supports VeNCrypt encryption. The Unix viewer has many new features.
Gapito, Gnome Parallel Terminal, allows to run several SSH or telnet sessions in parallel, replicating user input over all of them. It is very useful to administrate clusters of machines.