The Evernote logo is an elephant because it’s the note-keeping app that never forgets.
Evernote has played a vital role in keeping my research, notes, and plans organized. It conveniently indexes notes and even images, making them searchable in a clear, well ordered fashion. A paid account, which I use, will give you effectively unlimited storage plus indexing of the text in images and PDFs.
Sadly there’s no offline mode on the Chromebook but it’s immensely useful all the same.