NIS was pretty cool back in the day, in fact Linux still uses remnants of it to let you pick your namespace sources (nsswitch.conf). Unfortunately the NIS protocol transmits passwords with low security over the wire.
Had a lot of "fun" recently setting up the Microsoft Active Directory System as the sole user account management system for both Windows and Linux in a hierarchical Windows domain environment. Managing users on both platforms was then done through ADS alone. The trick was to install the NIS schema extension to ADS but not run the NIS service, then use the Samba Winbind and Kerberos protocols instead.
It was such a cheap, elegant and secure solution that any large organisation should be able to apply if they are looking to phase out Windows desktops in favour of Linux and keep the burden of managing two disparate user account systems down.