First, navigate to Google Docs and log in using your Google account. You can continue to the next step after you are presented with your documents listing.

Hover over any item in your documents list and click the Actions menu that appears. From the available actions in the menu, click on “Download...”.

A dialog window will pop up. Select "all items" near the top.

In the "All Items" section, you may have to wait a few seconds while Google counts the number of items you're downloading. Then, you'll be able to selectively pick the which files you want to keep. When you're finished configuring things, click the Download button at the bottom of the dialog window.

Depending on how many files (and how large they are), you may have to wait while Google compresses your files and makes them available for download as a zip file. If you don’t want to wait, click the “Email when ready” button to have the download link emailed to you. However, if you stay on the page, your download will begin automatically once the process is complete.

And now, you wait.