Would be a good idea to ask some interesting questions regarding Linux and the Games industry, or related to these topics, then choose a couple of the most creative answers.
Things like: “Do you think other digital distribution platforms like Origin will get ported to Linux if Steam seems profitable.”.
Or more technical like: “Backward compatibility has been a problem when Microsoft moved from Windows 98 to Windows XP due to kernel differences, will this be a problem for Linux as well if more games will arrive, and what could we do to solve it”
Or even a little more broad like: “If gaming on Linux would be more general, could the same thing happen to other Operating Systems like BSD or Haiku”.
Just some general suggestions.
Also i think it would be cool to theme the contests with things related to the products you could win, so something related to Left For Dead (or just zombies in general, let people think of the most creative way to keep alive in a Zombie Apocalypse) if the product is Left For Dead.