"The Cygwin tools are ports of the popular GNU development tools and utilities for Windows 95, 98,and NT. They function using the Cygwin library which provides a UNIX-like API on top of the Win32 API."
That pretty much says it all, doesn't it? Cygwin brings useful tools like SSH, head, tail, bash and many others to the Windows world. Another attractive component to Cygwin is a powerful development environment: GCC, a C/C++ compiler for *nix and, in this case, Cygwin.
For information regarding Cygwin or SSH in Cygwin, please visit the Cygwin Website. Also see Andrew Hunt's Cygwin + SSH Wiki.
Please note: I had originally set this site up because documentation for SSH on Windows was sparse at best. Now, the documentation and setup scripts included with Cygwin make it very easy to get SSH on Windows working.
Please also check out OpenSSH for Windows for a quick, easy OpenSSH on Windows (with required Cygwin components) Installation.