Gokul Calendar is a handy app developed by Gokul Bhajan & Vedic Studies (GBVS) containing the holy days for Gaudiya Vaishnavas. It can be refreshed with data for every year.
It was started from the children of GBVS during their Android Development course and then made into an app.
For the first version, the data is only for USA. Later versions will support for other locations.