Is it possible to do a whois type search on someones last name to find out what website domains they registered?
No its not possible. What you can do though is do a reverse lookup on the IP where they are hosted and get the number of site on that IP and try to link which one belongs to the person you want to spy on Ani
It is possible to an extent. That surname had better be very unique though. If you go to http://whois.domaintools.com/digitalpoint.com , you will notice in the DomainTools Exclusive section that you can find out what other domains are owned/associated by the registant. To the best of my knowledge, this is the only place that does it. It's not free though.
It is a useful tool of sorts I guess. I remember trying to get a domain name and trying may comibinations. Turned out, this one guy had taken every single alphabet prefix and more of that word. The domaintools site currently shows him as - the guy doesn't even bother parking the domains