The online ftp client, http://www.net2ftp.com/, I have been using for a while, to get around my works firewall and update my website is for some reason inaccessible. For anyone looking for an alternative, http://www.web2ftp.com/ is quite nice. I used to use it previously, and then the host shut it down due to misuse, which was the reason I started using net2ftp in the first place. It is not as feature rich as net2ftp, but it does what it says on the tin.
UPDATE (3rd July '08)
I tried to log in to web2ftp this morning and got the following error.
Web2FTP deactivated !!!Sorry, but we had to deactivate our free service Web2FTP.We have introduced new security functions as logging User actions, Ip-Numbers and blocking whole IP-Ranges from Asian and African networks, but some users continued to upload Phishing sites. We are working on a new solution for registered user.Leverkusen, 03.07.2008