The Underscore Archives

Not quite 'an FTP client in a browser' but you might want to take a  
look at Fancy Upload.

> Swf meets Ajax for beautiful uploads. The release of the long  
> awaited MooTools upload widget thats allows queued multiple-file  
> upload including progress bars. Try it out, the unobtrusive file- 
> input replacement.
>
>

http://digitarald.de/project/fancyupload/

--
petef