Years ago, there was a Lab that let you save email attachments directly to Drive. It was one of my favorites and sorely missed when it became unavailable. Well, the feature is back and I think you will find it very useful for getting attachments into your Drive account quickly.
From Google Blog:
You're probably used to downloading email attachments, but each of those files takes time to download, eats up space on your device, and can get buried deep inside your "Downloads" folder. With today's update to Gmail, you can skip that whole process. Instead, you can view attachments and save files directly to Google Drive without ever leaving Gmail, making it easy to access them later from whatever device you’re on—computer, phone or tablet.
The next time you open an email with attachments, you’ll see new previews of the files at the bottom of the email, from photos and videos to spreadsheets and PDFs.When you click on one of those previews, a full-screen view of the image or document will appear. You can read, search for a particular phrase, and even browse through multiple attachments right in Gmail.
You can now also save your attachments directly to Drive simply by clicking the Drive button that appears when you hover over the preview. Of course, if you prefer to download the attachment to your computer, you can—just click the arrow button.
This new attachment experience is available on desktop and will be rolling out over the next week. If you’re one of the more than 120 million active Drive users, you know that saving your files to Drive lets you get to them from any computer, phone or tablet.