I've written up a HOW-TO on setting up a diskless NetBSD system.  Right now
I only have full details for hp300.

<http://www.netbsd.org/Documentation/network/netboot>

Please mail me if you'd be interested in filling in the platform-specific
sections for the following architectures (and any others that are capable
of running diskless that I may have missed):
sun3
sparc
vax
next
macppc (imac?)

Thanks go to the many people that have provided me with information,
testing, and code while I wrote this up:

     * YAMAMORI Takenori, for porting rbootd to SunOS, Solaris, NEWS-OS,
       HP-UX, and a few other OSes and for leaving a trail of
       documentation in his wake;
     * Peter Maydell, for porting rbootd to Linux and providing copious
       documentation on the process;
     * Klaus Klein, Rainer Kopietz, Stan Brown, and Peter Radcliffe, for
       figuring out how to get the NetBSD rbootd to work under FreeBSD;
     * Wes Brown, for hints on how to configure HP-UX to use rbootd;
     * Peter Radcliffe for additional FreeBSD and Solaris info, as well
       as proofreading;
     * And, Brian Chase, author of The VAX Network Booting HOWTO on which
       much of this HOW-TO is based.

  -- MW