gFTP is a free multithreaded FTP and SFTP client for Unix-like systems.
It has the following features:

  Distributed under the terms of the GNU Public License
  Written in C, has a text interface and a GTK+ 2.x interface
  Supports the FTP, FTPS (control connection only), HTTP, HTTPS, SSH, and FSP
  Multithreaded to allow for simultaneous downloads
  File transfer queues to allow for downloading multiple files
  Bookmarks menu to allow you to quickly connect to remote sites
  Supports downloading entire directories and subdirectories
  Extensive connection manager with FTP and HTTP proxy server support
  Supports resuming interrupted file transfers
  Supports caching of remote directory listings
  Supports connecting to a FTP server via command line parameters
  Supports associating icons with particular file extensions in the list boxes
  Sorting capabilities in the file list boxes
  Can restrict files in the list boxes to a particular file specification
  Supports viewing and editing of local and remote files
  Allows for passive and non-passive file transfers
  Supports FXP file transfers (file transfer between 2 remote servers via FTP)
  Eliminates buffer overruns from malicious FTP sites

WWW: http://gftp.seul.org/