Cozi is a FREE online calendar helping you organize your family, classroom, or other activity. Cozi and Tango Card have teamed up to give away a $50 Tango Card every day through December 24, and TWO $250 Tango Cards on December 25! Share Cozi, via email, Facebook, Twitter, or face-to-face. Then send an email to firstname.lastname@example.org.
Winners are selected from entries the previous day, so I think (not sure) you have to enter everyday.