Yup. Cross-platform, too. At least iOS and Andrdoid. Sorry Windows people. And Blackberry. Remember when everyone had a Blackberry? And now nobody. Maybe they can rebrand and make a comeback like Nokia.
Allegedly, they're for Wiccans and/or people interested in moon phase photography, but I'm kind of suspicious now.
Some even tell you what time moonrise/moonset is, and if the moon will be visible. I don't know if that effects...things...but can't hurt to know, right?