lftp is a command-line file transfer program for UNIX and Unix-like systems. It started as a FTP client but it also supports FTPS, HTTP, HTTPS, HFTP, FISH, and SFTP. The program also supports FXP and simple BitTorrent protocol support.
lftp(1) is a file transfer program that allows sophisticated transfer of multiple protocols such as FTP, FTPS, HTTP, HTTPS, HFTP, FISH, SFTP, FXP and BitTorrent. Like bash it has job control and uses the readline library for input.
It has bookmarks, a built-in mirror command, and can transfer several files in parallel. It was designed with reliability in mind. LFTP is free software, distributed under the GNU GPL license.
A complete list of features can be found here, and a more detailed description of the software here.