Vodafone rolled out some fairly decent prepaid 3G broadband plans back in May. Now that deal has got cheaper, with $99 scoring you a stick and 1GB of downloads.
As we've often noted when discussing 3G broadband, prepaid options make sense if you're just looking for an occasional use option (like holidays or work trips). The main restriction is how long a given block of credit lasts: with Vodafone, the answer is 30 days (assuming you don't top up in that time).
The Vodafone bundle requires you to activate before the end of December to get the 1GB allowance, which makes it a pretty transparent play for Christmas present buys. The only other issue to consider with Vodafone is that its connection software verges on the Satanic, but that's a criticism that can be levelled at almost everyone in this space.