If you apply for a Virgin Flyer Credit Card by May 31 and spend $5000 within the first 3 months, Virgin Money is offering a bonus 20,000 Velocity points. This is on top of the usual "four free flights" offer, where four times a year you get 2 for 1 flights on Virgin Blue. Note that you still have to cover the credit card booking fees on the second flight.
Normally, the card also earns rewards at one Velocity point per dollar spent up to $1500 a month, however, after the first $1500 the earn rate reverts to a much lower 0.5 points per dollar, so those putting a lot of monthly spend on their card may be better off looking elsewhere.
The annual fee is $99. The interest rate on cash advances and purchases is 20.99% which is pretty high, though you do get 44 days interest-free on purchases. There's also a 2.9% balance transfer offer for 6 months.
The card also comes with travel accident insurance and a concierge service.
This offer an exclusive partnership with Mozo.com.au and not available on the Virgin Money site. For more general card info, check out http://virginmoney.com.au/credit-card/flyer-cards/
Pay $99 annual fee, must make $5000 spend to get 20,000 Velocity points.
Not worth it unless you think the free second flight makes up for it.