Distributed Password Files?

mrbill asks: "I'm looking for a distributed password/group file system for a mixed network - we've got Linux, HP-UX, IRIX, and Solaris (some using shadowed password files, some not) systems here, but I need to keep the passwords on the machines synchronized to a "master" machine, *without* using NIS/NIS+. Rdist is not acceptable either, since obviously a HP-UX machine cant use a password file straight from an IRIX box, etc. Suggestions? "