Ah, work scheduling. I recall with fondness long hours spent in the Texas A&M Commons building trying to schedule two weeks of 24-hour emergency desk service around the personal and scholastic lives of a dozen sophomores. No wait, not fondness, that's not right. What's the word I'm looking for? Ah, that's it: abject loathing. Maybe if we had something like Doodle, I wouldn't have spent four hours playing Time Slot Monopoly every other Wednesday.
Doodle is a web service that lets teams instantly see and assign who's doing what, when. It's intended for retail and support jobs that always need one or more people on during specific hours, but you can adapt it to almost any situation where work or attendance needs to be shared over time. Doodle has been around for years, but for some reason the developers are just now getting around to making an Android app. It appears to have been worth the wait: all of the standard functions of the web app are available in the Android version. The interface is clean, and the app includes built-in chat and polling tools.
Single users can have a personal Doodle calendar for free (with advertising), but to really see the benefit your business needs to pay for a team account. Ask your boss about it if you're tired of wiping marker dust off of your fingertips. Doodle is compatible with Android 4.1 and later.