Google Docs viewer is a handy tool that lets you view different files directly in your browser, including email attachments and online documents. Earlier this year the Google Docs viewer added even more file formats that it can handle. Instead of downloading a file to your computer to view it, you can simply view it in your browser. This is especially handy when you just want to view a file and not have it sitting on your hard drive.
Google Docs Viewer can now also view the contents of a ZIP or RAR file. You can view the files that are inside the ZIP or RAR archive and even download individual files.
This is a very handy feature that I have already used a few times.
Source:
Google Tutor - Viewing ZIP and RAR Files Using Google Docs