I am not aware of a service like this on the web. However, I do see the need and I will make that service available soon to the web! Internally I can do this right now. I would love to know if anyone has heard of such a service besides me!
So do the registrars. I've seen reference to plans to rebuild the WHOIS database to permit this type of search, but I don't know when/if it'll happen, and if it does, I'm not sure that there will be any public access permitted. I'm not sure if Net Sol should even have the "name" search as it stands available
>>I just went to NetSol & ran the "Name" whois on a company I know of that has about 20 Domain Names and it did not yield but 6 of them.
Most of the more advanced promoters tend to "cloak" their whois info as they don't want people knowing who they are or where they (especially in competitive searches). So if you are a competitor of theirs you will never know who the site actually belongs to.