I have recently taken over one of the Christmas challenges (I can't remember what it was called, if it ever had a name!). I think because we've been communicating by email, it largely went unnoticed on the 5+ boards.
Anyway, I've taken over from Ursula, and if you'd like to join, just drop me an email with your name, the amount you'd like to lose by Christmas, and your WI day. I'll send out a weekly summary email/spreadsheet, and we can all keep each other motivated!
Good luck for WI's this week