There is such a high demand for Oprah Show tickets that they run a Reservation Lottery System which first involves becoming an Oprah.com member. Once you've become a member, you can submit a reservation request for the day you would like to attend the show, then, after the reservation window has closed, you will be contacted via email if your request was excepted. Currently, the reservation window is closed but they should be accepting requests for October tickets soon.
In the meantime, Oprah is also offering the opportunity to get last-minute tickets to an upcoming taping. Right now, there are reservations open for the September 15th, 22nd, 23rd, and 24th shows in Chicago. To apply for one of these tapings, simply email the show and tell them why you should be a part of the audience.
Of course, Oprah always wants an enthusiastic audience which means they also fill seats by interest. For example, yesterday's audience, the ones who got the Australia trip, were all Oprah super-fans. Right now, they are looking for Liza Minnelli fans, teachers and parents with kids in public school. But, before you start applying for tickets, be warned, The Oprah Show has one, very strict, rule: you can only attend one show per season. Choose wisely!