man, they are really getting some cool tools
you can view what domains someone owns by the name on their whois
This mine, but you have to pay $110 for it, and I own more domains than this
http://www.domaintools.com/registrant-search/?&and[]=Jace+Byers
someone else I just tried had 20 domains and it was $79, so it is definitely a sliding scale on pricing
can be pretty valuable info though if you need it for some reason