Virgin Mobile's new Simple plan is clearly aimed at people who use phones as, well, phones: the big selling points are no flagfall and a flat 15 cent/minute rate that applies to 105 international destinations as well as Australia. Just don't make the mistake of using it on its own with a smart phone.
The plan charges 15 cents per local text, and has a 90-day expiry (with credit rolling over if you renew during that period). But it only includes 100MB of data, and excess usage is charged at 0.2 cents per KB (that's $2/MB, which you could chew through pretty quickly). You can avoid that with one of its $10 data bundles (which gives you 1GB for 30 days), but you'd need to make sure you signed up for that first.
Recharge values are $19, $29, $49, $79 or $99. You can also choose an automatic recharge, which effectively turns the plan into a no-contract postpaid option.