Domain Names Name Registration Search Domains Register

For example, I'm trying to figure out how many domain names are registered to John Doe. I'd like access to the WhoIs database so I can search for all sites that have the registrant John Doe and have a list returned to me.

I know I can enter a website, like www.OneMonthFree.com, into a domain registration firm like GoDaddy and use their WhoIs database to find out the registrant of a specific domain, but there are some 59 million .com sites and I really don't have that much time. I want to reverse that process and research on name or address or phone number or other searchable field.

Naturally, I'd like to search for free, but pay sites are OK.