The server itself will have to have that ability. There isn't really a 3rd party tool to do what you want.
Two ftp servers come to mind. But I don't know if there is any MacOSX support for them yet.
1> NcFTPd from
www.ncftp.com
This server is fairly easy to setup, but I have found it to be fairly buggy, as of last Feb. 2001. Mind you, I think it was a fairly new release, and the author had considered that version to be a work in progress. Almost 8 months later, I imagine that is is considerably more stable.
2> ProFTPd from
www.proftpd.org
This is my personal favorite. It is a little more complex to setup, but it is worth the effort, even for simple sites. It is very stable, and stable. (did I mention stable?) You could equate this to being the FTP world's version of Apache. As matter of fact, if you have experience setting up apache, then you will be right at home with ProFTPd. ProFTPd has all sorts of plugin modules that allows you to do reporting. In many cases, ProFTPd has the ability to let you do reporting thru any programming/scripting language you want.
Both servers do reporting in realtime. Both will report all sorts of good information. ProFTPd, however, is far more flexible at generating output. NcFTPd is far easier to setup. NcFTPd wasn't that stable. NcFTPd requires a license (although, it is free if you want to use it to serve no more than 2 connections), ProFTPd is opensource (very free).
My $0.02
bob..