Chrome: Google Drive has had offline access to files for a little while, but the process wasn't automatic. With a new update rolling out to users today, all your Google Drive files that you create will automatically be stored for offline access.
First, the automatic syncing only works if you're on Chrome OS or using the Google Chrome browser. You also need to have offline access enabled and the Google Drive web app installed. Once that's all set up, every time you create a file in Google Drive, it will automatically save it to your hard drive so you can access it anywhere. If it's enabled on your account, you should see the "syncing items" box on your main Google Drive page.