WinSCP Free SFTP, SCP and FTP client for Windows (license: GPL)
BitKinex all-in-one FTP/SFTP/HTTP/WebDAV client. (freeware, development discontinued)
HTTrack is a free (GPL, libre/free software) and easy-to-use offline browser utility.
WebDrive map a network drive or mount a device to FTP, SFTP, WebDAV, Amazon S3 or other cloud servers.