FireFTP – Free FTP For Firefox
FireFTP is a free, secure, cross-platform FTP client for Mozilla Firefox which provides easy and intuitive access to FTP servers. After it installs, FireFTP is available in the ‘Tools’ menu within Firefox. This package is very useful for anyone who needs to transfer files to an FTP account.

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.