The following systems are owned by other players:
http://www.swat-portal.com/php/forum/index.php?page=Thread&threadID=23843
Custodian is the only one you really need to worry about, but until you pick what "roleplay" (i.e., police, pirate, smuggler, etc) and are in a clan, I don't think we need to worry about it much.
Just watch out for the pirate sectors, I think we're good up to level 50 as "freelancers" though.