NNTPSwitch is a NNTP content router. It's aimed at  high-performance 
news servers for ISPs and Usenet resellers. NNTPSwitch forwards client
connections to multiple backend servers to get its actual articles. 
Depending on the backend server type, all NNTP commands and extensions
are supported, including (remote) authorization. Accounting is supported 
in a user-friendly matter for data limited NNTP connections.

WWW: http://www.nntpswitch.org/