PuTTY is a free implementation of Telnet and SSH for Win32 and Unix platforms along with an xterm terminal emulator. It is one of my must-have utilities that I use when administrating Unix boxes.
If you are using PuTTY on Windows you should check out PuTTY Session Manager. It is a utility that acts as a 'Launcher' for PuTTY sessions. It reads your configured saved sessions and allows you to organize them into folders and launch multiple PuTTY sessions at once.
You can download the latest version of PuTTY Session Manager here: http://puttysm.sourceforge.net/