IETF Secure Shell (secsh) Working Group
Contact information and papers of a group standardizing the SSH protocol.

OpenSSH
An open source SSH client and server.

OpenSSH on Windows
Port of OpenSSH server and client for Windows.

SSH Communications Security
Extensive information about the SSH protocol. Has a variety of SSH products for sale, including clients, servers, and VPN software.

SSH Master FTP Site
Binaries for SSH1 and SSH2 clients and servers for Windows and Unix.

SSH Patch Repository
NCSA's collection of patches for SSH.