MarsClock is an alarm clock that lets you see times for all three of NASA's Mars rovers -- Spirit, Opportunity, and Curiosity -- as well as the InSight lander and the new Perseverance rover. You can also set alarms in Mars time, either as one-shot alarms or as alarms that will repeat every sol (that is, every Martian day). This app is released for free by a (former) rover driver on NASA's Mars missions. Enjoy it!