Saw this one while scanning through my RSS feeds. In case others miss it, you can go to Dominoes and try to win a 360:

http://www.dominos.com/home/xbox.jsp

Supposedly if you order online (a Pizza) you are shown whether or not you win. You can also click the little link in the lower right corner, and play without ordering. Ten given away every day, and the contest runs from now until December 12th. If you don't win, you'll likely get a 48-hour free Xbox Live® Gold membership.

I don't have a 360, so I thought I'd share my code if someone wanted to use it:

How to get your Xbox Live® Gold 48-Hour Free Trial.
Your prize package includes a 48-hour free Xbox Live® Gold membership.*

Your activation code:
KGFP4-JCM3T-GWMFP-MCMF7-XBK7J

To activate your 48-hour free Xbox Live® Gold membership, follow the steps below. Go to step 4 if you already have an Xbox LIVE membership.

1. Connect Xbox 360® to a broadband internet connection.
2. Press the Xbox® Guide button, and in the Xbox 360 Dashboard, select Xbox LIVE.
3. Follow the on-screen instructions to create your Xbox LIVE account.
4. Sign in to Xbox LIVE from Xbox 360 Dashboard.
5. Select Xbox LIVE Marketplace.
6. Select Redeem Prepaid Card or Promotional Code when prompted, enter your code, and enjoy!

*48-hour free Xbox LIVE Gold membership allows access to online multiplayer gaming, but not to other Gold membership features. Check Xbox 360 game package to see if your game supports multiplayer. Free 48-hour trial offer is only for use on Xbox 360 and only available for new Xbox LIVE Gold subscriptions in the United States. At the end of your 48-hour trial period, your subscription will default to the free Xbox LIVE Silver subscription, unless you elect to extend your Xbox LIVE Gold subscription. Offer not combinable with other Xbox LIVE offers or rebates.

Also there is the following code if anyone wants it:

Need an excuse to get an Xbox 360? How about two free Xbox LIVE Arcade Games!
Buy and register a new Xbox 360 console. Then use the unique code below to get two free Xbox LIVE Arcade games. Xbox offers challenging puzzle games, family board and card games, retro arcade games and more. But the only way to get the free games is to get an Xbox 360. Like, now.

Here's your Xbox LIVE Arcade game code: xbx0807