Is there a php/cgi script out there that can take a list of domains and check them to see if any are not registered? I've searched but couldn't find anything.

I am 99% sure there is something out there already for this. Have you done a search on Hotscripts.com ?

How about this one: http://www.ep-dev.com/scripts-4.php :)

I use v3whois for check domain. They are now selling whois scipt. Information on following page.

http://www.v3whois.com/?p=buy

there are ALOT of FREE php whois script/classes, just google or phpclasses or hotscripts.

Although I hate Registerfly.com, I use their bulk registration form to search a list of 500 domains at a time. I think maybe Godaddy.com has this too, but I'm not sure.

You can use Registerfly.com's bulk domain checker, but DO NOT buy a domain from them, they're CROOKS!