PCMan is an easy-to-use telnet client mainly targets BBS users formerly running under MS Windows.
PuTTY is a free implementation of Telnet and SSH for Win32 and Unix platforms, along with an xterm terminal emulator.
WeirdX is a pure Java X Window System server.
The only professionally supported versions of VNC.
TightVNC is a free remote control software package derived from the popular VNC software.
UltraVNC is a powerful, easy to use and free software that can display the screen of another computer (via internet or network) on your own screen.
EchoVNC is a secure, "firewall-friendly" remote-desktop tool with support for VNC, Remote Desktop, and RAdmin servers and viewers.
BO2K is the most powerful network administration tool available for the Microsoft environment, bar none.
Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems, each with its own display, without special hardware.