Possibly the hottest actress working today (in both the ‘popular’ sense and the reprehensibly objectifying sense), Mila Kunis would seem like an obvious candidate for the role.
She’s got the sense of humour (vital), and so far she’s only been given the chance to show off her ass-kicking skills in lame movies (don’t blame yourself if you haven’t seen Max Payne or The Book Of Eli).
Likeliness? She’s busy on Sam Raimi’s Oz: The Great And Powerful at the moment, so scheduling could be an issue. That said, it could do her good to get a corset on the CV.