One of my most used apps is Dropbox, and for a limited time they are running a promotion. It's free to use so there's no reason not to try it out.
Take a tour. Dropbox is software that syncs your files online and across your computers. Put your files into your Dropbox folder on one computer, and they'll automatically appear on any of your other computers that also have Dropbox installed (Windows, Mac, and Linux too!). You can even download Dropbox apps for your smartphone or mobile device (iPhone, iPad, Android, and Blackberry). Everything in your Dropbox is available from theDropbox website, too.
Go to this link, and download it. For everyone that does, they will increase by storage capacity by 250MB up to 8GB, so you'll help me out too.