Google Drive launched with one feature missing -- the ability to save Gmail attachments directly to your Google Drive account. Well, thanks to Amit Agarwal, after doing a bit of work, your attachments will automatically be saved to your Google Drive.
The process requires you to copy a document from Amit's Google Drive account to yours, and grant it permission to monitor your Gmail account. You'll then have to create a Gmail filter that applies the label of GoogleDrive to any e-mail with an attachment that comes into your Inbox. If you prefer not to have every attachment saved to your Google Drive account, you can create a filter for specific people, being sure to include the attachment requirement.
Here are the complete directions:
1. Assuming that you are logged in to your Google account, create a copy of this sheet in your Google Docs (now Google Drive).
2. Open the sheet and you should see a new Gmail menu - click Initialize and grant the necessary permissions. This is your sheet (see source code) and you are not sharing your Google credentials or data with anyone else.
3. Next go the Gmail menu again and select Run. Close the Google sheet and you are done.
Now, if you're a bit skeptical of allowing a random document access to your Gmail account, I can't blame you. I was as well. But, to eliminate any fears of stolen passwords or unauthorized use of your information, Amit has also posted the source code (linked to in the second step above) to the script that actually sends your attachments to Google Drive. Everything the script does stays inside your Google account. In other words, your data and credentials aren't sent to a remote server somewhere.
Going forward, every two minutes the script will monitor your labels and pull any necessary attachments into a folder called Gmail in your Google Drive account.
Not everyone has made the switch to Google Drive, so if you're looking for a way to automatically save any attachments to your Dropbox or Box account, give Attachment.me a look