as long as duplicate content is not an issue...

or if it is you could implement a 301 redirect for all but the canonical hostname.

Have you considered _default_ [httpd.apache.org]?

The thing is, I want to let people create custom sites using php. I need a simple way that all domain names which point to my ip via DNS open up an index.php. In that file I read the hostname and serve content depending on the domainname.