In Chrome OS, you can view Microsoft Office files within a browser. In the regular versions of Chrome browser for Windows and OS X you can do the same, but only after installing the beta extension Chrome Office Viewer.
This extension works invisibly and comes pre-installed on Chrome OS. When a final version of this extension is released, perhaps it too will come already installed on Chrome, or its functionality will be embedded into the browser’s code.
What’s even more intriguing is that current development versions of Chrome OS also include rudimentary technology to let you edit your locally stored Excel and Word files.