Web-based ftp clients

[vestero]

You will need to trust them with your username and password of course.

Surftp.com Pretty straightforward. Just fill in the blanks and go.
http://www.surftp.com/

Web2ftp.com A similar service. This one offers a link at the bottom
of the page to test web2ftp with a sample login to a ftp in Germany.
http://www.web2ftp.com/