Probably .info, it's not managed by any national government.
http://www.iana.org/domains/root/db/info.html http://www.afilias.info/about-us
Regardless, stupid law, Team America strikes again!
Under US law it is now possible for the US to seize any of these domain names -- and it will continue until the international organization in charge of this system (ICANN) says "oh, that's retarded, we're changing the system so that the US doesn't host .com and .org domains."
We had to fight against two acts proposed in the US which would have made it possible for the US to build a sort of DNS firewall to deny access to other domains from users working within the US -- our own rough draft of the Chinese firewall, if you like. (That was SOPA and PIPA.) But this other right was granted earlier than that, and is now being used to chilling effect.
EDIT: Just read about BitCoin! Sounding better and better now!
EDIT: This is wrong, see peteri's post.
.org is essentially the same as .com, owned by the US government and managed by Verisign.
So far the US has not publicly tried to drop wikileaks.org, forcing WikiLeaks migrate to a TLD that is clearly outside US reach. Maybe they wouldn't want the bad press.
I'm wondering what is possible if I simply have a relationship with a reseller in the US (e.g. the one with the superbowl ads, or eNom), but my TLD registrar is outside of reach. I assume they could make the reseller drop the contract, or terminate it.