It depends on who you want to hide from. 

If you just want to hide from the general public, you just have to have a private registration.  Most domain registrars offer it for an extra fee. 

If you want to hide from governments, that is harder.  The big thing is that you have to have cooperation of the web host and domain registrar.  You have to find one of each that will allow you to have a private registration that they won't reveal to anyone, including governments, without a very good reason.

Swiss might be good.  France is an option. 

An even better way to do it might be to work everything through a proxy.  Have a friend of a friend set up the web site.  Pass them the files and the posts.  Never come in contact directly with the site at all.

If you don't need control of the site yourself, and just want to post information, such a site already exists.

http://wikileaks.org/