I just commited twisted.ftp, and I think it is pretty neat. Not everything is supported, but it should work with any ftp-client out there. To get it up and running, just 'mktap -r ~/myftp', where '~/myftp' is the directory you want to leech; the default is '/pub/usr/local'. Start the server with twistd, and ftp to your server on port 2121. Login as 'twisted' with the password 'twisted'. The password is stored plaintext, so be careful ;) Now have fun with upload and download.
What I haven't told you: I haven't tested it under linux, so I'm curious if it works at all. Also, test it on the most bizarre ftp-clients you have (MSIE works), and tell me how it fared.