Mayan Calendar is an Android app that displays current date (or any date in Gregorian calendar) in Mayan "Long Count" calendar.
This app can convert any date in Gregorian Calendar into Long Count calendar and back. See app Screenshots.
Read wiki for more information.
I originally wrote this in 2010 for my Google G1 — the very first Android phone. It had a tiny screen and fairly limited UI capabilities, but I still have good memories of working with it. While the app itself is very much of its time, the core logic is still relevant: the Mayan number glyph handling and calendar conversion code can be easily extracted and reused if that’s what you’re interested in.