I've read that getting a very small drill bit (#76) and applying some slight side pressure and flicking out may work.
I've also personally had limited success (read: one time) of very carefully and VERY gingerly drilling out the middle of a broken-off headphone jack with a tiny drill bit, then extracting with dentist tools. I'm not suggesting this as the BEST course of action, but it is possible. If you attempt, make sure you have a way to secure things so they don't move about when you're drilling. (A vise with soft pads perhaps) and be careful.