I just recently found SilveOS (formerly windows4all) which basically brings the familiar desktop OS (I think it’s modeled on Windows 7) into the cloud (there are others of course such as eyeOS, but SilveOS is easier for me to maneuver into since the desktop is a familiar one). You can save your settings and documents edited in SilveOS by registering for a free account which should take only 2 minutes of your time, or you could sign-in as a guest which will give you the same functionalities except for backup and restore and the ability to save your personal settings in the cloud.
The Good:
Improved security when browsing. The OS is completely sandboxed.
Available for free.
Access your files anywhere.
Forget about hardware requirements. If you’ve got a browser, just move on.
Hassle-free registration.
Complete support.
Available as add-on for IE, Firefox, and Google Chrome.
Basic applications including a browser, text editor, notepad, and a few games, twitter, youtube viewer and more.
The Bad:
Requires Silverlight installed.
Only supports applications in.xap format
No/Slow internet connection it’s rendered useless
The Compromise:
Future support for applications not in .xap format
Wide range of available programs in .xap format found in their forums
Works just as well as regular desktop OS