Are you an Xbox 360 gamer who doesn't have an Xbox Live Gold membership, and yet is somehow still playing Halo 3? Then good news: Silver members are being treated to free Halo 3 multiplayer all weekend, in celebration of the recent release of the Mythic Map Pack (or in other words: "Hey non-paying XBL members -- wouldn't it be totally cool to upgrade to Gold and enjoy this all year round!?").
Note that the weekend promotion applies only to Halo 3, so there's no, say, Gears of War 2 multiplayer in your immediate future, Silver members. The promotion ends on Monday, April 13, at 9AM PST, to be exact. So that means you have, as of this writing, about 43 hours left of sweet, sweet game time. Milk it for all it's worth.