Amaysim had added a cap plan to its existing pay-as-you-go option, and it's a pretty good deal: $39.90 for 30 days of unlimited Australian calls, texts and MMS, plus 4GB of data.
That price point puts it well below most other "unlimited" cap plans, while it offers a higher data allowance than most of them. Unlimited access to Facebook, Twitter, LinkedIn, Foursquare, eBay and MySpace is also included, and there's no separate voicemail charges either. If you exceed the data allowance, extra usage is charged at 5 cents per megabyte (or you can purchase a separate 1GB data block for $9.90).
What you don't get is any credit for international calls or texts, or the ability to call 1300 or 1800 numbers or make video calls. Customers who sign up for a postpaid plan can make those calls but they're charged separately as an extra item.
There's no contract requirement, though (unsurprisingly) there is a fair use clause that excludes business or excessive usage. The data can be used for tethering (a current technical issue means that the personal hotspot option on iPhones doesn't work, but Amaysim says that will be fixed in the future).
The service utilises the Optus network, and you'll need to pay $2 for a starter SIM in a retail store (or $5 online, though that includes pay-as-you-go call credit). At Amaysim's existing rates, the unlimited plan would be better value than pay-as-you-go if you make more than 10 minutes worth of calls a day (and that's without factoring in the data inclusions or text messaging).