XBOX Australia is currently running a promotion where AU Silver members can get 1 month of Xbox LIVE Gold for $1. To get it, login to your Silver account and choose the 1 month membership option.

http://www.xbox.com/en-AU/pm/goldoffer1dollar

Note that after the month it will auto-renew at standard rates, but you can of course cancel or change your renewal before then.

Offer only available to Silver Xbox LIVE members.

(via InsiderX AU)