SSH & Windows

If you want to enable people to connect to a Windows server via SSH, a good choice is VShell from VanDyke software, at http://www.vandyke.com/. It has a built-in SFTP server, port forwarding, and more. It's a SSH2 server package.

SSH & Macs

Mac SSH is a free SSH client, and it allows you to choose your FTP client too. It's based on the original NCSA Telnet code, so it's fairly stable too. You can get it at http://www.macssh.com/.

There's also Nifty Telnet SSH, downloadable from http://www.lysator.liu.se/~jonasw/freeware/niftyssh/.