PuTTY is a free SSH client.

PAC is a SecureCRT/Putty/etc (connections manager with automations) equivalent for the Linux world.

Gnome Connection Manager is a tabbed SSH client.

OpenSSH is the premier connectivity tool for remote login with the SSH protocol. It encrypts all traffic to eliminate eavesdropping, connection hijacking.

SecureCRT is an SSH and Telnet client and terminal emulator.