http://itunes.apple.com/us/app/timetours-chichen-itza/id417634504
TimeTours: Chichen Itza sends you back to the time of the ancient Maya. It is a travel app, educational of course and entertaining with treasure hunt, quiz and more games all with GameCenter achievements and leaderboards.
TimeTours right now has a huge Maya Calendar Countdown with lots of goodies (incl. promo codes):
http://www.time-tours.com/daily/
App is updated regularely with new content and minigames and will feature episodes from 'The Time Traveler's Kids': http://www.time-tours.com/kids/