SkyDrive is a service from Microsoft that allows you to synchronize anything in your SkyDrive folder on your desktop with 7GB (or more if you're willing to pay) of online storage AND any other desktop you configure. There's a great article on it here.
The way it works is simple. You sign up for a Windows Live account (which you will use to access your stored data) and download the SkyDrive client for your desktop. During setup is will ask you to log in to your live account. Once it's set up, you will get a SkyDrive folder on your computer. Now any document you put in that folder will automatically show up in you SkyDrive online storage as well as any other computer you install the SkyDrive client onto.
But wait, it gets better. Log in to your SkyDrive account and find a Word document that you just uploaded. You can now click on it and it will open in Microsoft's online Word application. Same thing for Excel, PowerPoint, and OneNote. Cool! I can even edit document on my smartphone! Sometimes, technology really is great.
So, with that set up, if my hard drive crashes, all of my data is safe online and on any other computer I have the client on. If I need to access a document away from my computer, I can do it from any web browser.
It keeps my data both safe and accessible - AND - it takes care of itself. No manual copies. No saving in two places. No flash drives to carry around.
It's simple, easy to use, and easy to maintain. It's almost hard to believe it came from Microsoft.