TightVNC

TightVNC is a free remote control software package. With TightVNC, you can see the desktop of a remote machine and control it with your local mouse and keyboard, just like you would do it sitting in the front of that computer.

TightVNC is:
free for both personal and commercial usage, with full source code available,
useful in administration, tech support, education, and for many other purposes,
cross-platform, available for Windows and Unix, with Java client included,
compatible with standard VNC software, conforming to RFB protocol specifications.

With TightVNC, you can:
cut your expenses and save your time on traveling,
help your friends and family to solve problems with their computers remotely,
make sure nothing wrong is happening on your computers when you are away.