Windows: In the newest version of Windows, you can create a picture password that you unlock with a series of taps or drags. Try using this to drill yourself on information you want to learn.
The picture password works with a series of three motion. You can circle, tap or drag across certain parts of the photo. To unlock your machine, you need any combination of three of these gestures. By using photos of something that you're trying to learn (like the periodic table example above), you can quiz yourself every time you unlock your computer.