Christ, Rockstar would have been my pick for a dead cert. Can't believe that's not up there. I think Namco might be a decent shout, then there are a few other big ones like THQ. But seriously, if EA, Rockstar and Bioware aren't up there, smurf knows who could be.
edit: Might be an outside chance of guys like Atlus and Tri-Ace showing up here as well. Also, Sega. IDK, it's a tough one considering what is and isn't there.