If you're looking for an easy way to save and organize the PDF, Word, and other file attachments you receive in Gmail, try Gmail to Drive. Gmail Attachments to Drive is a Chrome extension that you can use to have your attachments automatically saved in your Google Drive account. See how it works in the Tekzilla video below.
Applications for Education
If you accept emailed assignment submissions from your students, Gmail to Drive could be a great tool to help you organize those submissions. Set up a folder in your Google Drive account just for attachments to keep track of the files your students send to you.