Conversation starters at a really classy dinner party/ball?!
People love to talk about themselves. (Let's face it—we're all ultimately more interested in ourselves than anyone else.) So notice something interesting or unusual about the person you want to talk to—something they're wearing, their hairstyle, an interesting piece of jewelry, etc.—and ask them about it.
Once you get them going, just be a good listener. Say "Really?" and "That's interesting" and things like that. Echo back some of the things they tell you: "So your grandmother gave you that pin?"
Don't start talking about yourself until THEY ask you something about you. By that time, if you've done your job, they'll really be interested in you, rather than just going through the social motions.
People love good listeners because they're so rare. (Some people are so desperate to be listened to, they pay psychologists big dough to do it.) It's a real skill that's worth developing, and it'll serve you well nearly everywhere you go.
I recently read a great book called HOW TO BE A PEOPLE MAGNET that talked a lot about the power of listening, and about other good ways to connect with people. You may want to check it out. Cheers, Ander