How do I offset an output

I'm playing with a 1302 linear hall effect sensor. It has an output that is about 1/2 supply voltage when not in a magnetic field.

Depending on polarity of magnetic field it outputs less than half or more than half of supply.

What kind of circuit would I use to make its normal 1/2 supply voltage output equal to zero volt? I'd need it to swing + and -.

I'd be thrilled if some one would give me the keywords to search for this circuit.

Thanks,

Wes

-- "There is only one basic human right, the right to do as you damn well please. And with it comes the only basic human duty, the duty to take the consequences." -- PJ O'Rourke