Ask HN: What can MtGox customers do now to defend against ID theft?

Re: http://www.zerohedge.com/news/2014-03-11/isnt-it-ironic-mtgox-hacker-demands-ransom-exchange-users-not-reveal-their-personal-

Now that it seems your MtGox passport scan is being sold, what are some steps to take in order to protect yourself?

What can be done to minimise the prospects of finding out your credit rating has been hijacked, or your webservice accounts hacked using your personal details?