Evernote is an advanced note-taking app with features that have real practical value. For students, I would argue that the ability to separate thoughts into "notebooks" is Evernote's key feature. Once notebooks are created, students can easily insert items, such as typed/written notes, web site links, audio files, and attachments. The very idea of keeping an entire class full of material in one location in the cloud is powerful enough, but Evernote goes one step further and allows access to one's stored material on almost any conceivable fixed (PC or Mac) or mobile device. There is a free version, but I recommend the monthly upgrade to the paid version to unlock all the advanced features. Evernote occasionally runs a promotion where serious discounts can be realized.
Nozbe is a project and task management app that contains serious tools for off-loading important thoughts before they disappear from your mind. Now, I understand there are many ways to capture one's important thoughts via software applications. Apps like Reminder, Todoist, Notes, Wunderlist, and many others are quite good at the simple task of capturing a thought. Even Evernote could serve this purpose. However, Nozbe is built to capture, organize, and operationalize thoughts into separate projects. If you are familiar with the Getting Things Done process, Nozbe fits into this space because its structure is linearly organized to move actionable ideas ("tasks") into a project framework.
Imagine all your classes are projects and throughout the semester you conveniently add actionable, class-related items into these projects. This is the essence of how Nozbe works. Research has confirmed the real power of the human brain lies in its cognitive and creative functions; however, it is limited regarding its ability to be a long-term store of information. For the latter, Nozbe fills the gap and shines very bright.