Khan Academy is a fantastic resource for learning, with videos on a wide range of topics, including match, science, finance, and the humanities. A mobile app for the iPhone and iPod touch as well as the iPad can keep you learning on the go.
The app is free for both types of devices, but the iPad version has more options. On the iPad, you can download videos to watch them offline, view subtitles, and log in to your Khanh Academy account. iPhone users can only view the videos, but that's still enough to help continue your education while you're sitting in traffic or on vacation.