Up and coming mobile operator AmaySIM knows that Australians love their cap plans, so has added to its pay-as-you-go offerings with a $40 a month cap plan that looks pretty tough to beat.
For $40 a month you get unlimited national talk, text and MMS, unlimited access to Facebook, Twitter, LinkedIn, Foursquare, eBay and MySpace, plus 4GB of data to use every month. What's missing is credit for calling 1300, 1800 and international numbers, although if you make a lot of those calls there are better plans on other carriers for you anyway.
Excess data is charged at 5c/MB, or you can add on a GB for $10. Throw in the fact that data can be used for tethering (altough apparently the personal WiFi hotspot doesn't currently work on iOS devices), and this is easily one of the best cap plan deals on the market. So long as you live in an Optus coverage area, of course.