Cyberduck – FTP and SFTP Browser for Mac OS X
Cyberduck is an open source FTP and SFTP (SSH Secure File Transfer) browser licenced under the GPL with an easy to use interface, integration with external editors and support for many Mac OS X system technologies such as Spotlight, Bonjour, the Keychain and AppleScript. It works great with Smultron.

WinSCP – Free SFTP, FTP and SCP client for Windows
WinSCP is an open source free SFTP client and FTP client for Windows. Legacy SCP protocol is also supported. Its main function is safe copying of files between a local and a remote computer or server. It also has code editing capabilities and can launch Putty as a terminal client.