So I'm gonna give you a recap of what I've seen as the best advice on this page, and then add a couple of my own. (I got a job at the first place I interviewed so I figure I did something right)
1) Pants. Very important.
2) Be ready to answer all the sterotypical questions (I thought there was no way they'd ask why I should be hired, but damn it all, they did)
3) Ask questions, but be careful not to sound like that guy in lecture who questions the professor to get brownie points for paying attention. Ass-kissing rarely gets you anywhere.
4) Voice an extreme, almost visceral hatred of Amazon in general, and the Kindle in particular.
5) Again, emphasis on pants. Double-check before leaving home.
My points
1) When asked about your weaknesses try looking hesitant to talk about them. Then bust out with "Well sometimes I'm just too damn awesome."
2) Man-flirt. Hard. Unless the interviewer's a woman, then try not to stare at her tits.
3) Just be yourself... Oh, wait... Ummm, be a more mature, less ADD version of yourself... Oh, wait... laws of physics and all... nevermind point three. You're a theatre guy, make it happen.
Hope it was of some help without being too offensive.