There's a bunch of these online – like Lasttix – but it's curious how much a show's success depends on the image of success. If word gets around that a show is "selling out fast", people are more likely to front up for a ticket; but – as producers will tell you – if a show is advertised as two-for-one, audiences sometimes shy away, following the logic that a show must be pretty ordinary if they have to lure audiences in with discounts.
That's why it pays sometimes to stick your head in at Halftix on Swanston Street. Although, for the sake of image, a producer might not want their show advertised at a discount online, they might still make tickets available to those who front up in person on the day. Word to the wise: they only accept cash here.
Arts Centre Melbourne have their own version of this: tixatsix. Head to the box office on Level 5 of the theatre's building (under the spire) from 6pm each day and join the tixatsix line to purchase $30 tickets to a show that night. A minimum of 20 tickets are on offer each night, and you won't know which shows – across their entire program of theatre, ballet, contemporary dance, cabaret, circus, opera and more – are up for grabs until you get there. Your limit is 2 tickets per person.