So I found some application from the Nokia store. It seems nice but it only offers Old Calendar Easter date. A bit problematic since it is Palm Sunday today in my church.
We only follow the Julian calculation for Pascha in the Orthodox Church (unless you're weird...lookin' at you, Finland and Estonia!
). If you want an app like you describe in the Gregorian form, I highly doubt you'll find it from an Orthodox source.
I am a Finn. I wonder what my bishop thought if I told him that we must switch to the traditional calendar so that I can have cool mobile apps...
Btw, AFAIK Estonians of Constantinopolitan variety follow revised Julian calendar nowadays.