Now that the long time favorite, and extremely popular DropBox has a really tough competitor with the newly released Google Drive (previously named Google Docs - minus the regular file storage ability and some other new features) everyone's having a bear of a time trying to figure out which service to use, and for good reason; while DropBox is extremely generous with space for it's users and has robust features, Google Drive is close, but still has some catching up to do and room to grow, nonetheless it's already shaping up to be excellent, and with this GeekDrop trick to get free space on Google Drive, you may no longer need to worry about which choice is the clear one.
Each Gmail account that you own provides an automatic 5GB of Google Drive space. Google doesn't mind if user's have multiple Google Drive accounts, so all that needs to be done is to "stitch" all of your Gmail accounts together to provide one big account, so to speak.
The Geeky Details - You can skip reading this part if you want:
What we're going to be doing here in essence is creating a single shared folder on each secondary Gmail account and then sharing it with our main Gmail account, the one that we plan to use all of or most of the time, the "big pot". Since the shared folder is being shared from a secondary Google Drive account to our main account, the secondary account is the Google Drive account that'll be taking the "space hit". That is, any files stored on your main account into one of the secondary's shared folders will deduct the space from the secondary's allotted space and not your main account's space.
Next, navigate your way to the Sharing menu item as shown above, and click it.
Enter the email address of the Main Gmail / Google Drive that you want all of the free space on into the edit-box. Make sure the "Can Edit" button is checked so that you can delete / rename / edit files in that folder from your main account, then click the Save button.
After saving you should see the main account's user name in the list of user's who can use the newly shared folder. Click the Done button.
If you did everything right you'll also see a new icon on the shared folder that represents it's being shared with other users.
That's it! Now for each secondary Google Drive account you've shared a folder with your main Google Drive account you have another 5GB of available space. The more you add, the more free space you get!
Once you've done so, you'll be able to use those folders from within Windows (or MAC, Linux, Android, iPad, iPhone) as any of your other folders.