Kasablanca - " Kasablanca is an ftp client, written in c++, using the kde libraries. among its features are
currently encryption (auth tls) support, fxp, site bookmarks, and queued transfers."
FileZilla - Handy, easy to use and with a good layout, makes this FTP client worth consideration. Unlike many of the "zilla" sounding programs that contain ad and spyware this one contains neither, being open source you can even examine and modify the code if you should so desire. Better yet it doesn't need to be installed, on first run the program will ask if you would like settings to be recorded using the registry or using an XML document.
Open Source
Leech FTP - Excellent basic FTP program that's free and worked flawlessly for me.
Freeware