Gmail Drive is a third party software extension originally thought up by Richard Jones  that allows you to use your Gmail account as though it is a drive attached to your local machine.  You have the ability to drag and drop files into that drive and retrieve the files from another machine if necessary.  Let's take a look at how it works.

Once installed the drive shows up in My Computer or Computer in Vista.

Once installed you can double click the drive and you will be prompted to login with your Gmail account credentials

Splash screen while Gmail logs you into your account.

Once logged on the drive appears as an empty Windows Explorer view, just drag and drop a file into the drive.

You will get this indication screen while the file is being uploaded to your Gmail account.

Now when you log into your Gmail account you can identify the files as they will be labeled "G-Drive GMAILFS".

I find this application handy for transferring smaller files so i am able to access them anywhere there is a web connection.  It is easier than opening a session to email yourself the file.  Just keep in mind this will use up your allotted Gmail account space.  There are also some restrictions to this application.