FTP server, web based frontend, user management, upload notification

Does anyone know if this exists?

Basically, I need to build a FTP server.

I would like to give employees in my company access to a web based front end where they can create user accounts, set private home directories and pass login information to people outside of the company so that they can upload files to the FTP server.

As a "nice to have" feature, when files are uploaded with that account, I'd like the person who created the account to receive an e-mail to let them know that new files have been uploaded.

Google'ing around hasn't returned very many results. I figure that this is a pretty common thing in Linux based offices so I'm hoping that one of you guys can point me in the right direction.

Any help is greatly appreciated.