Both U.S. and some European countries can score either a free Xbox Live Arcade game or downloadable content for upgrading to gold Live. Each offer requires silver Live members to upgrade to a gold 12 month subscription prior to January 5th and the account upgrade must be done online. Then, once the subscription is paid in full, you'll get to select from a variety of free XBLA games and DLC that's specific to each offer. Free goodies including N+, Zuma, Marble Blast, H3 Legendary Map Pack and more. Click the offers below to get all the details and get learned about the specifics.
[Via Joystiq, Thanks Jonathan]
Source - Free gift for U.S. Xbox Live
Source - Free gift for European Xbox Live