I always thought the QDP was a handy spot for all kinds of thingies concerning qmail.
Since the original QDP has been off the net for years now, i mirrored it.
Qmail Documentation Project (not maintained)
Single UID Mailbox HOWTO
Bruce Guenter's RPM packages adapted for RedHat 9:
Qmail HTML manpages:
qmail HTML manpages
qmail 3rd pty
The qmail newbie's guide to relaying
Selective relaying with tcpserver and qmail-smtpd
Bernstein replies to qmail slander
Other stuff by Dan Bernstein:
daemontools a daemon that keeps daemons up and running
ucspi-tcp a replacement for inetd
djbdns an UDP dns server
publicfile an http / ftp server