Ask HN: What are the most demanded IT certificate?

Hey, I've given the "chance" to choose one IT Certificate from O'ReillySchool (http://www.oreillyschool.com/promotion/february_2013.php) and I just wanted to know your opinion about what you think it's the _most demanded_ IT Certificate of the following:

-Linux Systems Administration

-Python Programming

-Perl Programming

-Database Administration

-Java Programming

-PHP/SQL Programming

-Client-Side Programming

-Web Programming

-Open Source Programming

The ones I want are: Java, "Open source programming" and Python, what do you guys think?