I have been using Dropbox for a few weeks now and really like this application. It allows you to sync files between computers. It works no matter what operating system you are using Windows, Mac or Linux. So if I am working on a Word document on my Windows PC at work I can place it in my Dropbox folder and it is upload to the Dropbox server. When I get home and turn on my Macbook the Word document will automatically download to my Mac.
If your not home the file is still available in your Dropbox account and available for download from a web browser. The best part is the first 2GB are free and 50GB is $99 per year.
So click on this link and try Dropbox for yourself.