InterNetNews is a complete Usenet system.  The cornerstone of the package
is innd, an NNTP server that multiplexes all I/O. Newsreading is handled
by a separate server, nnrpd, that is spawned for each client.  Both innd
and nnrpd have some slight variances from the NNTP protocol.

WWW: http://www.eyrie.org/~eagle/software/inn/