REQUEST: Advice on pre-pay data SIMs.

I will be in and out of Australia a lot over the next 6 weeks.

I want to pick up a bunch of pre-pay SIMs, most importantly for data.

Data only plans are fine actually, but a voice line could be handy.

Any advice as to what to get, which carrier, where to get them, etc.?

I have a Galaxy Nexus (pentaband GSM) and a Sony Ericsson Xperia Mini Pro on 850/1900/2100MHz.

I'd like to get them both online if possible, and I tether with both of them.

** EDIT **

Thanks for all your help guys.

I got a Telstra USB stick and a Vodafone USB stick, took the SIMs out and put them in the phones.

I activated Telstra over the phone. Although it was a data only chip, it allowed me to call the activation number.

Activation required ID, I gave my California driving license number and was up and running in 5 minutes.

Vodafone requires online activation, which is a chicken and egg situation. I got online tethering my laptop via the Telstra SIM, and activated the Vodafone chip with my UK passport number. However, it didn't work in any phones. Customer support couldn't figure it out. It was apparently successfully activated and all okay.

A friend here gave me another Vodafone SIM and that worked OK, no idea why the other one didn't.

So for anyone else in the same position, get the Telstra USB stick pack. I had great reception in Perth & Sydney.