The new PokerStars deposit offer is valid until the end of January 2014 and is the biggest sign-up bonus for new players.
Deposit $20 or more and get $20 worth of free play and an extra $14 which can be cleared by earning 1VPP to release each $1 daily for 14 days.
PokerStars Bonus Code: FREE20+14
Also running this month is the PokerStars January Challenge where players can complete a daily challenge to win entry to a daily $15k all-in shout-out tournament.