Going to school online is what all the cool kids are doing. And the really cool kids are doing it without paying a dime (if you can stretch the definition of "school" to services offering commitment-free classes to thousands of people at once who don't earn college credit). Coursera is one of the more popular options for this non-traditional learning, and now it's got an Android app to make it even easier.
Coursera offers real college and university courses from real schools, allowing dedicated students to get useful learning without the huge time and money it usually takes just to get access. True, you don't get anything tangible except a mark of completion (and employers are unlikely to take that on faith since it all works on the honor system), but if you're looking to increase pure skill and knowledge, it's a pretty good way to invest your time. The service currently offers over 600 courses from more than 100 institutions, ranging from Scandinavian Film and Television to Cryptography classes from Stanford. There's a heavy focus on practical and in-demand skills like programming and education.
The app itself allows you to browse the course list and enroll in classes, stream video lectures, and download class materials. Notifications for upcoming courses will make sure you don't miss that one class you wanted - Coursera's system uses real professors and TAs, so class availability is on a non-standard schedule. The UI looks pretty functional, but some early reviews indicate that there are issues with lecture streams.
Coursera's app is a free download. You'll need an account and an Android 4.0 or higher device to get in on the action.