I have an idea to make the upcoming challenges based on Christmas. Assuming that it will be easier to complete with a good amount of credits to be awarded, this is good during the holidays. They look like this:
-Weekly Challenge-
12 Games of Reachmas = Win 12 games in Invasion
-Daily Challenges- (for Christmas Day)
Deck the Swords = Kill 50 enemies with Energy Swords
Miracle on ONI: Sword Base = Kill 34 Elites in Campaign
Jingle Frags: Kill 11 enemies with grenades in a multiplayer matchmaking game
Rudolph the Alpha Zombie = Kill an alpha zombie seven times in a multiplayer matchmaking game
Normally the credits will be displayed with the challenge, but they will act like a present, which means the amount will be unknown until they successfully complete the challenge.
Also, another gift that everyone should get is 12250 cR just for playing Reach on Christmas Day.
[Edited on 12.16.2011 10:42 AM PST]