I know. I know. Clouds r evil. In general, I agree. I prefer to own hard copies of my software.
Just the same, I am coming around to the advantages of online storage & apps as a means for backup, convenience and security. While it's vital to burn shit to media, for me, it's also nice to have online backups for my backups. That way I don't have to go digging through hundreds of CDRs or play transfer-files-from-good computer-to jumpdrive-to reformatted computer. I can just go online, open my account and download my stuff.
When it comes to online OS, I look at it this way: If I'm out of town and using someone else's computer, I can access my stuff, manipulate my settings and install what I want to install without ever storing a thing on a machine that isn't mine, except some easily-erased cookies and temp files. As well, when I'm at the bookstore, sipping coffee and enjoying free wireless, I can open up my cloud OS and surf the net without worrying some sniffy little kid is gonna bring harm to my precious baby laptop.
Anyway, I got interested in online OS a few months ago and I found one that I really like:
http://www.glidedigital.com/It's got 30 gigs of free storage and while it's a little slow on my ancient notebook, it flows pretty nicely. I get a free email account and I can upload music and photos and (if I were so inclined) it has all kinds of software for multi-user conferencing: