As digital notebooks become common forms of external memory, keeping track of these volumes of content is also becoming increasingly difficult. Information visualization tools can provide note-takers with an overview of their content and allow them to explore diverse sets of notes, find and organize related content, and compare their notes with collaborators. To ground the design of such tools, the authors conducted a detailed mixed-methods study of digital note-taking practice. They identify a variety of editing, organization, and sharing methods used by digital note-takers, many of which result in notes becoming "lost in the pile." These findings form the basis for the authors' design considerations that examine how visualization can support the revisitation, organization, and sharing of digital notes.